History of American football positions American football positions have slowly evolved over the history of American football . From its origins in early rugby football to the modern game , the names and roles of various positions have changed greatly , some positions no longer exist , and others have been created to fill new roles . Origins in rugby . Being variants of 19th century rugby football , American and Canadian football position nomenclature has its origin there . Early rugby did no more than distinguish in tactic s between the great bulk of the players who played as forwards and the relative few who played back defensively as " tends " , as in goaltender s . After a while , the attacking or at least counterattacking possibilities of playing close behind the scrimmage ( which later came to be called " scrummage " ) came to be recognized , and some players stationed themselves between the forwards and tends as " half - tends " . It being seen that the players outside scrimmage ( the " pack " , i . e . the forwards ) were not limited to a defensive role , the tends and half - tends were renamed " back " and " half back " positions . As the game became more sophisticated , backs positioned at different depths ( i . e . distances behind the forwards ) were further differentiated into half back , three quarters ( the fraction 3 / 4 ) back , and full back , according to English and Scottish nomenclature , or quarter back , half back , and full back in the Irish nomenclature . In rugby the English - Scottish nomenclature was eventually adopted worldwide , with the word , " back " , often omitted for brevity from the half back ( " half " ) and three quarters back ( " three quarter " ) names , and " fullback " as a single word . In some systems , " five - eighths back " has been added . ( The illustration here , of singular forms , should not be construed as indicating the number of players in any of those positions , nor is the fraction in the name at all proportional to the actual depth of the position ; they indicate only a quirky form of ordinal number , not cardinality . ) Having the backs at different depths facilitates passing movements in which the ball is tossed from one player to ( usually ) the next closest , such that each back receiving the ball in turn can be running forward and yet not ahead of the player who threw it , forward pass ing of the ball being illegal . Because of the involvement of the 3 / 4 backs , such a movement is often called a three - quarters movement . It was the Irish nomenclature of quarter back , half back , and full back that came to North America for use in what was to become the dominant native form of football . The terms became hyphenated and eventually unhyphenated single words , " quarterback " ( QB ) , " halfback " ( HB ) , and " fullback " ( FB ) . The lack of quarterback in the English - Scottish nomenclature for rugby led to the position name " scrum - half " to distinguish the halfback playing close to scrimmage ( renamed " scrummage " or " scrum " ) from another who would " stand off " from it or " fly " away — the " stand - off " or " fly - half " . Early Canadian football . Around 1900 , at the same time , the number of players on a Canadian football team was reduced to 14 , the number of players in scrimmage ( formerly packing all the forwards ) was fixed at three per team . It became customary for six to eight of the other players to continue as what might be known in rugby as loose ( non - packing , i . e . not binding together ) forwards who in Canadian football formed " wing line s " on either side of the scrimmage . In scrimmage , each team had one centre scrimmager flanked by two side scrimmagers . The side scrimmager s bound with hands and arms to their centre scrimmager . The centre scrimmager of the side entitled ( and required ) to do so would put the ball down in front of him for play by scrimmage , while both sets of three bodies each ( " formed into one compact body " as the rules specified ) were crouched and shoving forward at each other , probably meeting at the shoulders as do the front row of forwards in rugby ' s set scummage . Depending on the rules , details of the time for the particular circuit of Canadian football clubs , the centre scrimmagers would either contend with their feet for the ball , or one would be entitled to foot it first ( usually heeling it back ) , while the other team ' s would try to spoil the ball ' s delivery . The backfield of three to five players continued to use the nomenclature ( see above ) of quarterback , halfback , and fullback , and sometimes included one or two flying wing s ( see below ) . When six played on the wingline s , their positions were called " inside wing " , " middle wing " , and " outside wing " , arrayed in order away from the scrimmage . An additional player called " flying wing " could " fly " , between a position on the wingline outside the outside wing , and the backfield . However , the 14 - a - side game ' s rules never required certain numbers of players in either the winglines or the backfield . With the later reduction in sides from 14 to 12 players , and introduction of the thrown ( not footed ) snap , the positions of the three scrimmagers were replaced by a single position called " snap " . The position names in the winglines were retained for a while , but eventually replaced by the USA nomenclature , although it was not until the 1960s , that Canadian rules required seven players on the offensive line , unless they were playing short handed . Before that , only five were required on plays in which no forward pass was thrown , so it is likely that in such situations , one or both ends were replaced by or became a back . " Snap " became " center " and considered a wingline or line position . " Centre " even became the rule book designation of the snapper , although as in the USA version , there is no necessity that the player who snaps the ball have equal numbers of teammates flanking him or her on the line . More position names . A tendency was seen , from early on , for players to keep their position names even when playing out of that position . For instance , before the minimum number of players on the offensive line was fixed at seven , when players who would otherwise be in the line as guard s or tackle s played from offensive backfield positions , the formation was known as a " guard ( s ) back " or " tackle ( s ) back " formation . Meanwhile , another position name was introduced . Players were placed in the offensive backfield just outside of their ends , in a position that came to be called " wingback " ( WB ) . Formations with one or two wingbacks came to be called single or double wingback or wing formations . Over time , the typically fast back who played fullback , on offense and defense , was replaced by a heavier one who presented a greater threat to run with the ball more or less straight ahead , and to tackle his opponent trying to do the same . For this purpose , the player tended to be placed closer to the line than previously — often as far forward as the halfbacks ( the offensive backs then forming a letter T , sometimes called a " straight T " , later to distinguish it from slight variants wherein other backs did not form a line perpendicular to that from the quarterback ) or even farther forward . But the position kept being called " fullback " . On defense , this necessitated another position name for the fast back who played farthest back : " safety man " or simply " safety " ( S ) , representing the last defense against a breakaway play , and the position from which to field opposing kicks . Approximately , on defense , the quarterback and fullback exchanged positions from what they ' d been playing on offense , and the quarterback became the safety . Still , when at the beginning of the 20th century , a penalty was introduced for hitting the opposing kicker after a kick , the foul was at first called " running into the fullback " , inasmuch as the deepest back usually did the kicking . Confusion increased when the legalization of the forward pass made it more advisable for teams to defend with fewer on the line of scrimmage and more behind . Although the offense could no longer play " guard back " , for instance , the defense had no such limitations . A common defensive formation was the 6 - 2 - 3 or 6 - 2 - 2 - 1 , shown below arrayed against an offense ' s straight T : HB HB C FB _ _ _ _ E _ T _ _ _ G _ _ _ _ G _ T _ E _ _ _ _ E T G C G T E QB HB FB HB Note that the so - called center and fullback are playing left and right versions of the same position . The positions were later renamed " linebacker " . However , that did not become the usual way to name that position until platoon football became common , with players specializing in offense or defense , substituted according to which team has the ball . There seems to have been some tendency for defensive positions to be named for where the player would play on offense , although quarterback and safety formed an early exception . When linebackers are playing close to or level with the line , a somewhat reliable way to distinguish them from line players is that the defensive line players will be in a three - or four - point stance , meaning that they will be supported by one or both hands , in addition to feet on the ground , while the linebackers will have only feet on the ground . Line players with one or both hands on the ground are called " down linemen " ; typically all defensive linemen are so positioned . Alternate position naming schemes for an offensive formation are illustrated below in a version of single wing formation : HB HB FB E T C G G T E QB FB WB TB In the top illustration the center is flanked by guards in the 4 - 2 unbalanced line ( four players on one side , the " strong side " of the center , two on the other , " weak " , side ) as in a balanced line , leaving the tackles together . In the bottom illustration , the guards are kept " inside " by being next to each other . The end positions are fixed by rule , because " end " is a rule book term . As to the backfield , the top illustration preserves the principle of the names , reflecting distance from the line . However , the bottom illustration needs further explanation , having eliminated the halfbacks and introduced a new position name , " tailback " ( TB ) . Wingback has been described above , but the " WB " in the above illustration is deeper back than that position name would seem to warrant . That is because this is a " wingback deep " version of the single wing , and the position is named wingback because the player is named for his true wingback position as it exists in other versions . In this version the player may stand as deep as any other back , but there has been a reluctance to identify formations in American football as having more than one fullback ( or tailback — see below ) , although two - fullback systems were not uncommon at one time in rugby . What to make of the replacement of the other halfback from the top illustration by the fullback in the bottom one ? Well , if the wingback were playing in a true wingback position but named halfback , then the other " halfback " would be playing deeper and thus deserve the name fullback . Another justification is that the player positioned as the left halfback in the top illustration tends to have the fullback characteristics described above . But rather than call the faster , lighter back behind ( and in this formation , to the left of ) him a halfback and so contradict the distance - back - determines - the - name principle ( and rather than add rugby ' s three - quarters back ) , we call that player " tailback " — the tail of the formation , farther back than the fullback . Even when two players positioned to take a thrown snap in a single wing formation are level with each other ( i . e . at equal depth ) , the faster one ( usually playing weak side ) is often called the tailback and the more massive one the fullback . Note that the quarterback in this formation is not in position to receive the snap . ASCII art ( letter diagrams ) cannot show this fine a detail , but a quarterback in position to take a handed snap is allowed by rule to stand farther forward , in a place which would otherwise cause illegal confusion as to whether the player was in the backfield or the line . However , the popularity of thrown - snap formation s from about 1920 to about 1950 ( and the illegality of the handed snap in Canadian football when snapping by hand rather than foot was first prescribed in that game ) induced some teams to place the quarterback a little farther back , receiving the snap via a short toss . Even ASCII art is subtle enough to show the left end above a little farther from the nearest other line player of the same team than is the right end . Such a slight additional gap is said to be " flexing " that end , but does not produce an additional position name . However , when the gap is considerably greater , that is said to be a " split end " ( SE ) . That produced a position name when on offense a team played with one end split and the other not split — a " tight end " ( TE ) . The split end being specialized for going downfield to catch forward passes , it becomes more useful to differentiate the split from the tight end than between left and right end . Instead of wingbacks or conventionally placed halfbacks , an offensive team could have backs positioned wide of the rest of the formation , similarly to a split end , to be pass receivers . Such a back would be called a " flankerback " or " flanker " ( FL ) . A more straightforward use of the position name , " tailback " , is shown below in an offensive short punt formation , whose use , despite its name , is not confined to punting . Without rugby ' s three - quarter backs , the sequence of quarter - , half - , full - , and tailback makes do . The line shown is balanced with one split end . In such a case , the side with the tight end is sometimes said to be the strong side of the line , and hence of the formation , because the tight end is better placed than the split end to block , especially on running plays . An additional justification for calling that the strong side in the example below is that the backfield has more players on that side , although that will not always be the case , and in this case the positioning of backs does not produce strikingly strong and weak sides , as opposed to the single wing formation shown above . If the deepest back were a specialist in punting , one might substitute " P " for " punter " for the " TB " above . Age of confusion . The trend of naming offensive positions for the role or build of player in it continued . In some cases , this obfuscates important details . A recent diagram of a short punt formation for offense in youth football had no quarterback , but two fullback s at the depth of the QB shown above , and a halfback at the position labeled FB above . Some discussions of the single wing previously diagrammed claim it has no quarterback . And many is the time when a player in the farthest back position , in a formation similar to the short punt shown above , is referred to as quarterback ! Position names no longer needed to reflect any given player ' s combined roles on offense and defense when few played both ways . As a result , position naming on defense has become less confusing and more informative . However , position naming on offense , while tending to eliminate obsolete distinctions , has also tended to hide important ones and confuse others . Offenses and defenses continued to adapt to the increases in forward passing favored by the rules . Below is diagrammed a 3 - 4 - 4 ( or simply " 3 - 4 " ) defensive formation and an offensive formation it might line up against across the lines of scrimmage , as popular beginning in later portions of the 20th century : CB CB OLB ILB ILB OLB _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ E _ _ _ _ _ _ _ NT _ _ _ _ _ _ E _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ WR T G C G T TE QB WR RB RB Beginning with the defensive line , one notices a slight departure from previous nomenclature with the position labeled " NT " . Why not simply " T " ? The superfluous designator " middle " when the defense was playing with an odd number on the line less than seven , as in " middle guard " , was discussed above . ( This invites the unanswered question of whether , if the defense has an eight - player line , it includes a " left center " and " right center " . ) " NT " stands for " nose tackle " , " nose " having been introduced with guards to indicate a position " on the nose " of the opposing center , although " nose guard " had not been a popular term , probably because it suggested a piece of protective equipment . There is justification for the extra word , in that the tackle in a 3 - player defensive line could well play off center ; however , this distinction is not maintained with teams using such a tactic , so the position could and probably should be referred to simply as " tackle " — or " defensive tackle " ( DT ) in a player roster ( see below ) . The linebacker ( LB ) positions are straightforwardly distinguished as inside ( ILB ) and outside ( OLB ) . When there are only three linebackers , the one inside is labeled middle linebacker ( MLB ) , and the outside positions can instead be named as left and right . The defense ' s halfbacks have been renamed cornerback s ( CB ) , a fitting term given that they play at the edges or " corners " . The term has no spurious indicator of the depth as which they are positioned in the defensive backfield . Finally there are shown two safeties . In this case they are distinguished as " free safety " ( FS ) — also known as " weak safety " — and " strong safety " ( SS ) . The strong safety is on the side following the strong ( tight end ) side of the balanced offensive line ( see above ) , and has responsibility for covering ( guarding as a pass receiver ) the TE , while the free safety has no such coverage assignment . However , the coverage played by defense does not always easily allow assignment of such distinct names for safeties . A formation with more than two safeties could have them described by their relative geometric placement — outside , shallow , deep , etc . - but such is not general practice ; however , see the discussion of the " nickel " below . The offense is diagrammed in what was for some time referred to as a " pro set " - - " set " indicating that the players are stationary , although one back may go in motion from it . This particular version is said to have a " deuce " , " flank " backfield . From the description above of the straight T , this formation can be seen to be derived by splitting one end and moving the halfback on the opposite side to a flanker position . Instead of " SE " and " FL " for those positions , however , we see " WR " , for " wide receiver " . In the 1960s , teams would distinguish between flankers ( e . g . the New York Jets professional football club ' s George Sauer ) and split ends ( e . g . his teammate , Don Maynard ) on their player rosters . For a relatively brief period , game rules had been adopted in some codes , requiring different uniform numbers for line players from those of backs , and the position naming distinction carried on for a while after the rules were amended to require only certains sets of numbers for ineligible and eligible receivers of forward passes . It became commonplace for ends to shift into backfield positions and vice versa . By the 1970s , the common practice changed to refer to flankers and split ends both as wide receivers or , more colloquially , " wideout s " — they play from wide of the rest of the formation . Note , however , that the playing rules still distinguish between ends and back s on offense . There are differences as to the motions , the players in those positions are allowed to make , during and preparatory to their team ' s snapping the ball . At the time they snap the ball , the team is required to have seven players ( minus any number their side is playing short in Canadian football ) on their line of scrimmage , which includes split or tight ends , but not flankers or wingbacks . Meanwhile , the distinction between fullback and halfback was erased , each replaced by " running back " ( RB ) . That term became popular during the 1960s as well , although even into the 1970s , some playing the pro set kept the HB - FB distinction . So , for instance , in the flank formation shown above , those positions were named as in the straight T , while in the " split " version of the deuce backfield , the fullback occupied the other halfback position shown in the straight T . The distinction referred to the build of the players , the fullback being a stronger runner more or less straight ahead , and the halfback faster to attack the defense ' s flanks . However , on many teams there was no strong distinction between those backs , and since their major role was running with the ball , " running back " was most descriptive without maintaining a spurious geometric connotation that ' d become outmoded by their lining up in different depth relationships . Alternative names for RBs are " deep back s " and " setback s " , although the latter is disfavored because it has also been used for backs in general , both on offense and defense . There is , moreover , a generic term for the deeper - playing backs ( CB & S ) on defense : " defensive back " ( DB ) , appropriately enough . Note that the term excludes the linebackers , even though they be backs in the traditional sense because they are usually not on their team ' s line of scrimmage . There also exist the generic terms " defensive lineman " ( DL ) and " offensive lineman " ( OL ) , although the latter refers only to the interior linemen , excluding the ends because of their eligibility to receive forward passes . However , to this day many teams maintain the offense ' s fullback - halfback distinction , especially in " full house " backfields , i . e . those with a quarterback and three running backs , that is , no backs playing wider as wingbacks or flankers . This is confusing enough , when the fullback plays slightly forward of the halfbacks , as in the Y formation shown below , later used to run the wishbone system ( the backs forming a letter Y or a resemblance to a wishbone ) : FB HB HB At least , that one is an easy enough derivation to visualize from the original diamond , with the depth of the fullback inverted with respect to the halves . However , some formations have placed the heavy back even more starkly forward , to function as a blocker for the running backs . In the diagram below of the V formation used by Dartmouth College in the 1950s , the respective position names have been rationalized as " BB " ( a not - very - popular designation , " blocking back " ) and RB : RB RB ( The running and blocking backs can be seen to form a letter V . ) However , in its time the running backs were known as halfback s and the blocking back as fullback . Another such example is the I formation , shown below in a with - wingback version : FB TB The diagram shows the more geometrically rational designation of tailback behind the fullback . However , some would label the deepest back in this form of deuce backfield " HB " , considering one halfback to have moved behind the fullback , who is in both the role of blocking back and the heavy up - the - middle runner . Those who would emphasize the blocking role of the FB ( the " up back " ) might even label the deepest back , " RB " , with a BB instead of FB . Few , however , would use the straightforwardly geometric labels of QB , HB , and FB in that order from front to back . Note also that the wingback is on the wing of a tackle rather than an end . This is accepted nomenclature where an end is split ( " WR " above ) . The wingback is just behind and outside of the " interior lineman " ( line player other than end ) . However , it is not uncommon for a wingback to be outside the tight end in an I or other formation where the opposite end is split . In the power I formation , instead of the wingback shown above , there is another deep back in the traditional halfback position . That position in the power I is probably called " halfback " more than any other name . In the triple I , where all the backs are in one line perpendicular to the lines of scrimmage , one could hope for the backs to be called quarter - , half - , full - , and tailback in order of depth , but various names are probably used . The diagram below of an " ace " formation deliberately mixes terms / symbols for wide receivers : RB On the left are represented the more traditional and descriptive terms " end " and " slotback " ( SB ) . The latter is for a position that would be labeled " FL " , except that the back is in a " slot " between tackle and end ( instead of outside of the end ) , here illustrating a double " wide slot " formation . ( It is wide because the end is fully split , rather than merely flexed — see above . ) There being no tight end , there seems to be no need to label either end as split ; both are . But on the right , the slotback and end positions are merely labeled as wide receiver s . Note that the single running back here is shown to one side of the center - quarterback combination , but that " ace " RB could as well be directly behind them . In some cases , the specific terminology of certain coaches has made its way into the general parlance . Coaches , having no motivation to publicize their plans , usually adopt cryptic codes for certain positions , using letters , numbers , or short names for their convenience . One set of designations which has been making the rounds , as of this writing on Web sites , purporting to explain football is the letters X , Y , and Z to designate receivers . It is doubtful that many coaches agree on the use of these terms to designate specific positions consistently from play to play , and those letters do not seem to enlighten but only to obscure . ( One manual for football spectators , in the 1960s , explained that someone calling offensive plays in the huddle would point to primary , secondary , and tertiary receiver s while giving them those letters ; those designations would vary depending on the play , not on the positions those receivers occupied . ) However , one such letter designation has caught on recently : " H - back " , illustrated in the offensive formation below : HB RB Here the H - back is represented by the symbol , appropriately enough , " HB " . The H - back position is like that of the " wingback deep " position previously described in a version of the single wing formation , and here is shown behind a wingback to emphasize that , although more often the H - back and wingback , if there is one , are on opposite sides of the set . It is possible to say the abbreviation " HB " is already taken up by the halfback . The H - back does occupy a position about the same as the halfback in the diamond formation of the 19th century . It is likely that " H - back " is a term derived by back formation ( pun unavoidable ) from the abbreviation for halfback , although arbitrary letter designation by some coach is just as good an explanation . You may see an offensive formation like that below , described as one of three tight ends : RB RB However , it is labeled above as a version of the wing T , i . e . a T formation wherein one deep back has been replaced by a wingback . The description of its having three tight ends is absurd , inasmuch as a line can have only two ends , but comes about when the wingback position is occupied by a player most suited to blocking who otherwise usually plays tight end . If the extra blocker up front is actually in a line position , then , considering that a potential eligible receiver is being sacrificed , it would be better to conceive the formation as having an extra tackle or guard : RB RB In the same vein as a formation ' s supposedly having three tight ends , examine the shotgun formation below . This is similar to the short punt formation shown previously , except that potential forward pass receivers are more widely spread . It is therefore , like the double wide slot offensive formation shown previously , a type of spread formation : TB However , many would label the tailback above as quarterback , even though the position is clearly the deepest back ! Until 1960 , the formation above would have been called a double wing , and the tailback labeled a fullback , there being no need for the tailback designation when the backs assume so few intermediate depths . However , the deep back position above is usually occupied by a player who habitually plays QB , so the habitual position name tends to stick , as with the " extra tight end " . The identification engendered by the T formation of quarterback as someone who takes the snap is so strong nowadays that some describe the single wing formation diagrammed previously ( under " more position names " ) , wherein the quarterback is positioned behind other interior line players than the center ( and therefore cannot conveniently receive the snap ) , as having no quarterback ! Such descriptions may have the QB as BB , although the system used may involve that player considerably as a ballcarrier or receiver , not just a blocker . On defense meanwhile , an opposite philosophy to position naming is sometimes followed from that of the supposed third offensive end . Instead of the position name following the player to a different position , a new position name may be applied in such a substitution situation . This occurs when a team that usually uses four defensive backs ( counting cornerbacks and safeties ) adds a fifth , thus producing the " nickel " defense ( a nickel being a 5 cent piece ) . It will be said that the extra DB is the " nickel back " , even though coverage assignments will be redistributed , and therefore no particular DB is functionally or positionally in a " nickel " position , distinct from the other four . Nor , if a sixth DB is added , could one distinguish between the " nickel " and the " dime " back . However , if they are subbed in one at a time , an observer may apply " seniority " in naming one " nickel " , etc . A roster will usually simply list such players as S , CB , or simply DB . Making sense of it all . The trend away from geometric naming of the offensive positions has led to considerable confusion . It has been said that some coaches at low levels of football , having heard game descriptions that included a team ' s having " put their tight end in motion " , have done exactly so , and incurred the penalty for the resulting illegal motion . Because of the rules of the game , it frequently matters whether a player of the offense is on the line of scrimmage or in the backfield , and in those cases the descriptor " wide receiver " is insufficient and " end in motion " ( except in Canadian football , where they ' re allowed to be shuffling sideways along the line of scrimmage when the ball is snapped ) is nonsense , although it may reflect the way the player in question is listed on the roster . In describing the play in a National Football League game , one may hear the contorted locution , " The quarterback was eligible to receive a forward pass because he was in the shotgun formation " , when it would be far simpler to say that the team ' s eligible receivers included the tailback who took the snap ; the rules apply differently depending on whether the player is positioned behind the snapper to take a handed snap , or further back and hence in the backfield . One can delineate two types of useful nomenclature . One type is for such purposes as calling play - by - play on radio , in text , or as described to a blind person . Such a nomenclature focuses on where a player is when the teams line up for scrimmage , and can describe the formation overall . Such nomenclature is also useful for technical purposes — instructions for coaches , for example . In this type of nomenclature geometry predominates , and there are no paradoxes such as extra ends , ends in motion , or quarterbacks standing deep in the backfield . For many play - by - play purposes , some geometric details , such as whether a wide receiver is an end or a flanker , can be glossed over unless they come into play . If a wide receiver is described as being in motion , the announcer , in calling it " motion " , conveys it as legal play by a flanker , but if an end changes position , the announcer refers to the player as " shifting " instead . The advantage of speed in calling a game is manifest , and it is faster to say " Jones and Smith are split out wide left and right " than to specify that one is a split end and the other a flanker , or that both are flankers or ends . The other type of nomenclature describes players by their usual roles — a description that is more suitable in describing a whole game or season than play by play . Such nomenclature may be used on rosters or in scouting reports , for instance . While in 1950 , it would have been common to say , " This team needs a passer " , to include various positions from which a player might throw forward passes ( and a pro team might well have converted a college tailback into a quarterback ) , it does not seem to do much harm to say , " This team needs a quarterback " , in an era when one associates quarterbacks with passing and vice versa . On the other hand , it does not hurt at all to mention the skill , rather than the position , if it is really a skill that is sought rather than a " job title " . And if a team ' s standard formation is shotgun , nothing is gained by including " quarterback " in the roster if there really is not one . In describing defenses , there does not seem to be a need for dual nomenclature . Nobody sees a need to geometrically break down a formation of three safeties into strong [ side ] , weak [ side ] , and " middle " , for instance , although if a team is expecting a kick one might well specify positions of " deep safety " and " shallow safety " . The line and linebacker position names give role and geometric information about equally . In odd - man line formations , the adjective " nose " can be reserved to distinguish cases wherein the middle lineman is directly opposite the snapper from those where the middle defensive line player is offset , and " middle " is superfluous if the existence of the odd number of linemen has already been conveyed . See also . History of American football