Slash Terminology

Slash terminology has evolved over the decades since slash fan fiction first began to be shared in the early 1970s.
It is important to differentiate between the PUNCTUATION MARK (/) and the WORD (slash), as they originally meant different things and had a different evolution. 
Charting exactly how the symbol (/) began to be used, the word (slash) (stroke was a lesser used UK term), and words like "pairing" and "shipping" can tell us more about the history of fandom and provide insight as to who we are as fans today.
The term "slash" to designate a homosexual relationship in fan fiction came from the use of the / -- the virgule symbol/punctuation mark inserted between names. This practice probably began somewhere around 1977. Prior to this time, the virgule had also been used to designate stories that focused on non-sexual friendships between characters (today, a "&" is often used for friendship). 
Klangley explains:
Fannish tradition holds that the word "slash" originated with Star Trek The Original Series fan fiction, when K/S was used as the label for a story where the relationship between Kirk and Spock was laced with sexual tension, whether it was acted on or not. This label allowed fans to differentiate these sexual relationship stories from the ones about Kirk and Spock’s friendship, which were sometimes labelled using "&". As fandoms gathered around new films and television series, the "/" mark became common as an indicator of a sexual relationship between same-sex characters.
There are many, many instances of fans in the late 1970s, early 1980s referring to K/S as a very intense relationship story which in some (not all) instances crossed physical and emotional boundaries. 
It is extremely difficult to draw a line between the two or to determine when the first use of symbol "/" for a sexual story occurred. One clear example was early 1981 issues of A.P.B., a British Starsky & Hutch letterzine where there was vigorous debate between fans of "S&H" and "S/H." 
In September 1981, a fan in A.P.B. #6 used the symbol "/" as shorthand: 
The use of the single symbol "/" was so uncommon that in APB, it wasn't used until over a year later, in issue #14 that it was seen for over a year later, in APB #14. 
A British fan in late 1982 wrote: 
One of the earliest, perhaps the earliest, usage of the symbol "/" to specifically describe a sexual relationship between two characters was in a humorous limerick published in Obsc'zine #1 (March 1977). "Limerick" by P.M. Muelenberg printed in Obsc'zine #1 was dedicated "To the Kirk/Spock premise, may it rest in peace," referred to the USS Enterprise as "the celestial ship Thunderthighs" and posited that Captain Kirk might not survive an encounter with Mr Spock's Vulcan genitalia.
One example of how hard it is to draw a line between "slash" and "gen" was is this review of the 1980 gen zine, Enter-comm #2: 
An older term used in the U.K. was "stroke," which definitely meant slash. Many fans preferred "slash" for dramatic reasons. A contributor to the Starsky and Hutch letterzine S and H #18 (February 18, 1981) wrote: "Actually, my main complaint about S/H is the term 'Starsky *stroke* Hutch.' It is just too coy. I like *slash*. It sounds so masculine, like passion in the night and lust that strikes like lightning. *Stroke* sounds so cutesy. *Slash* sounds dynamic, dominant, daring, and exciting." This is also the very first example of the WORD slash being used; it was an extremely rare reference. It didn't become common in print for several more years.
Others preferred "stroke"; in 1992, one wrote that to her it seemed "very appropriate and nicer than slash."The LOC Connection #44 (August 1992). 
The / might be pronounced or implied, as "K slash S" or "K S." "...early S/H slash writers pronounced their pairing "ess slash [or stroke] aitch", while early K/Sers were (they inform me) saying "kay ess". From December 17, 2002 comments by Mary Ellen Curtin at ASCEML 
Use of / as an indicator of a sexual relationship became entrenched as new fandoms arose -- including (Starsky/Hutch), (Bodie/Doyle), (Blake/Avon) and so on. Eventually "slash" became the name of the genre itself sometime in the late 1970s, early 1980s. ‘A Usenet experience of the history of slash’, retrieved October 4, 2008
There is another early reference in the STW Directory #16, published in August 1977. There, a listing for Thrust describes it as a "Ultra Adult zine. K/S relation. SASE with age statement required." This is also the first time the term age statement was used in the STW Directory. 
Also in August 1977, a fan wrote a letter to Obsc'zine #2 referring to "Kirk/Spock", explaining exactly why a homosexual relationship in the long-running and meticulously written Kraith series was extremely out of character for that series."I am not trying to attack a Kirk/Spock sexual relationship in general. It is just that when an author uses terms from a particular 'alternate universe', that author ought, in my opinion, be limited by the boundaries of the universe that the terms imply. I don't believe that a homosexual relationship for Spock and Kirk is legitimate in the KRAITH universe, and I therefore object to certain aspects of "Aftermath"....in the KRAITH universe, Spock could never come to such a state. He has affirmed the continuity [in Kraith, a vitally important ritual to preserve and perpetuate Vulcan cultural values] and represents his family on the high council... As the series progressed, Spock became more and more Vulcan and certainly more respected and revered there. It is illogical that in such a universe Spock could come to view Kirk as an object of sexual desire." S. Bridges LOC on the story Aftermath published in Obsc'zine #1 in March 1977.Homosexual Vulcans are inconsistent with the basics of the Kraith universe, where it is established that Vulcan is extremely underpopulated to the point that birth control and abortion are both illegal and immoral. The only Vulcans who are forbidden to have children are those who missed the Affirmation of the Continuity ceremony.
In the November/December 1978 issue of Scuttlebutt, the editor of Dreadnought Explorations mentions K/S as a genre all its own: "Sure, maybe you're not Jean Lorrah. Or Spockanalia. Or writing Kraith. Or a member of the Landing Party Six. Or a K/Ser." from Scuttlebutt #10 Another early example is in Star Canticle #2 (June 1979) where the editor recommends several zines, some with this warning: "Please note: some of these 'zines contain explicit material and/or K/S material. If you object to one or the other or both, do not purchase the 'zines." These three zines were Alternative 2&3 ("K/S"), and Matter/Antimatter #2 and Mahko Root #2 (both with the notation "adult K/S"). The STW Directory in spring of 1981 had this disclaimer: "Adult = age statement required, K/S = Kirk/Spock homosexual premise." from STW Directory #25
 
Another look at the written record of fandom's early days fills in more pieces of the puzzle. According to fandom historian Klangley56:
==References==
Category:Glossary
Category:Slash Fandom