Common misconception partially coincident with rumor
English language
Irregardless is a word. Nonstandard, slang, or colloquial terms used by English speakers are sometimes alleged not to be real words, despite appearing in numerous dictionaries. All words in English became accepted by being commonly used for a certain period of time; thus, there are many vernacular words currently not accepted as part of the standard language, or regarded as inappropriate in formal speech or writing, but the idea that they are not words is a misconception. Other examples of words that are sometimes alleged not to be words include burglarize, licit, and funnest which appear in numerous dictionaries as English words.
African American Vernacular English speakers do not simply replace "is" with "be" across all tenses, with no added meaning. In fact, AAVE speakers use "be" to mark a habitual grammatical aspect not explicitly distinguished in Standard English.
"420" did not originate from the Los Angeles police or penal code for marijuana use. California Penal Code section 420 prohibits the obstruction of access to public land. The use of "420" started in 1971 at San Rafael High School, where a group of students would go to smoke at 4:20 pm.
The word crap did not originate as a back-formation of British plumber Thomas Crapper's aptronymous surname, nor does his name originate from the word crap. The surname "Crapper" is a variant of "Cropper", which originally referred to someone who harvested crops. The word crap ultimately comes from Medieval Latin crappa.
The use of the word faggot as a pejorative for homosexual men was not derived from the burning of homosexuals at the stake with a bundle of sticks. Homosexuality was never punished with immolation in either England or its colonies. The actual etymology is unknown; it may come from an insult for unpleasant old women, or from British slang for a student that does errands for their superior.
The word fuck did not originate in the Middle Ages as an acronym for either "fornicating under consent of king" or "for unlawful carnal knowledge", either as a sign posted above adulterers in the stocks, or as a sign on houses visible from the road during the Black Death. Nor did it originate as a corruption of "pluck yew" (an idiom falsely attributed to the English for drawing a longbow). It is most likely derived from Middle Dutch or other Germanic languages, where it either meant "to thrust" or "to copulate with" (fokken in Middle Dutch), "to copulate" (fukka in Norwegian), or "to strike, push, copulate" or "penis" (focka and fock respectively in Swedish). Either way, these variations would have been derived from the Indo-European root word -peuk, meaning "to prick".
The expression "rule of thumb" did not originate from an English law allowing a man to beat his wife with a stick no thicker than his thumb, and there is no evidence that such a law ever existed. The false etymology has been broadly reported in media including Time magazine (1983), The Washington Post (1989) and CNN (1993). The expression originates from the seventeenth century from various trades where quantities were measured by comparison to the width or length of a thumb.
The word the was never pronounced or spelled "ye" in Old or Middle English. The confusion, seen in the common stock phrase "ye olde", derives from the use of the character thorn (þ), which in Middle English represented the sound now represented in Modern English by "th". Early printing presses often lacked types for the letter þ, meaning that "þͤ" () and "þe" were substituted with the visually similar "yͤ" and "ye", respectively.
The anti-Italian slur wop did not originate from an acronym for "without papers" or "without passport"; it is actually derived from the term guappo (roughly meaning thug or "dandy"), from Spanish guapo.
Xmas did not originate as a secular plan to "take the Christ out of Christmas". X represents the Greek letter chi, the first letter of Χριστός (Christós), "Christ" in Greek, as found in the chi-rho symbol ΧΡ since the 4th century. In English, "X" was first used as a scribal abbreviation for "Christ" in 1100; "X'temmas" is attested in 1551, and "Xmas" in 1721.Music
Classical music
The musical interval tritone was never thought to summon the devil, was not banned by the Catholic Church, and was not associated with devils during the Middle Ages or Renaissance. Early medieval music used the tritone in Gregorian chant for certain modes. Guido of Arezzo (c. 991 – c. 1033) was the first theorist to discourage the interval, while rock musicians popularized this myth to justify their use of the tritone.
Mozart did not die from poisoning, and was not poisoned by his colleague Antonio Salieri or anyone else. The false rumor originated soon after Salieri's death and was dramatized in Alexander Pushkin's play Mozart and Salieri (1832), and later in the 1979 Amadeus play by Peter Shaffer and the subsequent 1984 film Amadeus.
The minuet in G major by Christian Petzold is commonly attributed to Johann Sebastian Bach, although the piece was identified in the 1970s as a movement from a harpsichord suite by Petzold. The misconception stems from Notebook for Anna Magdalena Bach, a book of sheet music by various composers (mostly Bach) in which the minuet is found. Compositions that are doubtful as works of Bach are cataloged as "BWV Anh.", short for "Bach-Werke-Verzeichnis Anhang" ("Bach works catalogue annex"); the minuet is assigned to BWV Anh. 114.
Listening to Mozart or classical music does not enhance intelligence (or IQ). A study from 1993 reported a short-term improvement in spatial reasoning. However, the weight of subsequent evidence supports either a null effect or short-term effects related to increases in mood and arousal, with mixed results published after the initial report in Nature.
The "Minute Waltz" takes, on average, two minutes to play as originally written. Its name comes from the adjective minute, meaning "small", and not the noun spelled the same.Middle Ages
The Middle Ages were not "a time of ignorance, barbarism and superstition"; the Church did not place religious authority over personal experience and rational activity; and the term "Dark Ages" is rejected by modern historians.
While modern life expectancies are much higher than those in the Middle Ages and earlier, adults in the Middle Ages did not die in their 30s or 40s on average. That was the life expectancy at birth, which was skewed by high infant and adolescent mortality. The life expectancy among adults was much higher; a 21-year-old man in medieval England, for example, could expect to live to the age of 64.
There is no evidence that Viking warriors wore horns on their helmets; this would have been impractical in battle.
Vikings did not drink out of the skulls of vanquished enemies. This was based on a mistranslation of the skaldic poetic use of ór bjúgviðum hausa (branches of skulls) to refer to drinking horns.
Vikings did not name Iceland "Iceland" as a ploy to discourage others from settling it. Naddodd and Hrafna-Flóki Vilgerðarson both saw snow and ice on the island when they traveled there, giving the island its name. Greenland, on the other hand, was named in the hope that it would help attract settlers.
In the tale of King Canute and the tide, the king did not command the tide to reverse in a fit of delusional arrogance. According to the story, his intent was to prove a point to members of his privy council that no man is all-powerful, and that all people must bend to forces beyond their control, such as the tides.
Marco Polo did not import pasta from China, a misconception that originated with the Macaroni Journal, published by an association of food industries to promote the use of pasta in the United States. Marco Polo describes a food similar to "lasagna" in his Travels, but he uses a term with which he was already familiar.
There is no evidence that iron maidens were used for torture, or even yet invented, in the Middle Ages. Instead they were pieced together in the 18th century from several artifacts found in museums, arsenals and the like to create spectacular objects intended for commercial exhibition.
Spiral staircases in castles were not designed in a clockwise direction to hinder right-handed attackers. While clockwise spiral staircases are more common in castles than anti-clockwise, they were even more common in medieval structures without a military role, such as religious buildings.
The plate armor of European soldiers did not stop soldiers from moving around or necessitate a crane to get them into a saddle. They would routinely fight on foot and could mount and dismount without help. However, armor used in tournaments in the late Middle Ages was significantly heavier than that used in warfare, which may have contributed to this misconception.
Whether chastity belts, devices designed to prevent women from having sexual intercourse, were invented in medieval times is disputed by modern historians. Most existing chastity belts are now thought to be deliberate fakes or anti-masturbatory devices from the 19th and early 20th centuries.
Medieval European scholars did not believe the Earth was flat. Scholars have known the Earth is spherical since at least 500 BCE. This myth was created in the 17th century by Protestants to argue against Catholic teachings.
Medieval cartographers did not regularly write "here be dragons" on their maps. The only maps from this era that have the phrase inscribed on them are the Hunt-Lenox Globe and the Ostrich Egg Globe, next to a coast in Southeast Asia for both of them. Maps instead were more likely to have "here are lions" inscribed. Maps in this period did occasionally have illustrations of mythical beasts like dragons and sea serpents, as well as exotic animals like elephants, on them.
Christopher Columbus' efforts to obtain support for his voyages were not hampered by belief in a flat Earth, but by valid worries that the East Indies were farther than he realized. In fact, Columbus grossly underestimated the Earth's circumference because of two calculation errors. The myth that Columbus proved the Earth was round was propagated by authors like Washington Irving in A History of the Life and Voyages of Christopher Columbus.
Christopher Columbus was not the first European to visit the Americas: Leif Erikson, and possibly other Vikings before him, explored Vinland, which is presumably both Newfoundland and the Gulf of Saint Lawrence as far as northeastern New Brunswick. Ruins at L'Anse aux Meadows prove that at least one Norse settlement was built in Newfoundland, confirming a story in the Saga of Erik the Red. Further, Columbus never reached mainland North America, only mainland South America (1498–1500) and various American islands.
It is unlikely that the Black Death in Western Eurasia and North Africa was caused by rats. Instead, it is more likely it was caused by human parasites such as fleas and lice.Vertebrates
Old elephants near death do not leave their herd to go to an "elephants' graveyard" to die.
Bulls are not enraged by the color red, used in capes by professional matadors. Cattle are dichromats, so red does not stand out as a bright color. It is not the color of the cape, but the perceived threat by the matador that incites it to charge.
Lemmings do not engage in mass suicidal dives off cliffs when migrating. The scenes of lemming suicides in the 1958 Disney documentary film White Wilderness, which popularized this idea, were completely fabricated. The misconception itself is much older, dating back to at least the late 19th century, though its exact origins are uncertain.
Dogs do not sweat by salivating. Dogs actually do have sweat glands and not only on their tongues; they sweat mainly through their footpads. However, dogs do primarily regulate their body temperature through panting. (See also: Dog Anatomy § Temperature regulation)
Dogs do not consistently age seven times as quickly as humans. Aging in dogs varies widely depending on the breed; certain breeds, such as giant dog breeds and English bulldogs, have much shorter lifespans than average. Most dogs age consistently across all breeds in the first year of life, reaching adolescence by one year old; smaller and medium-sized breeds begin to age more slowly in adulthood.
The phases of the Moon have no effect on the vocalizations of wolves, and wolves do not howl at the moon. Wolves howl to assemble the pack usually before and after hunts, to pass on an alarm particularly at a den site, to locate each other during a storm, while crossing unfamiliar territory, and to communicate across great distances.
There is no such thing as an "alpha" in a wolf pack. An early study that coined the term "alpha wolf" had only observed unrelated adult wolves living in captivity. In the wild, wolf packs operate like families: parents are in charge until the young grow up and start their own families, and younger wolves do not overthrow an "alpha" to become the new leader.
Bats are not blind. While about 70% of bat species, mainly in the microbat family, use echolocation to navigate, all bat species have eyes and are capable of sight. In addition, almost all bats in the megabat or fruit bat family cannot echolocate and have excellent night vision.
Contrary to the apologue about the boiling frog, frogs die immediately when cast into boiling water, rather than leaping out; furthermore, frogs will attempt to escape cold water that is slowly heated past their critical thermal maximum.
The memory span of goldfish is much longer than just a few seconds. It is up to a few months long.
Sharks can get cancer. The misconception that sharks do not get cancer was spread by the 1992 book Sharks Don't Get Cancer, which was used to sell extracts of shark cartilage as cancer prevention treatments. Reports of carcinomas in sharks exist, and current data do not support any conclusions about the incidence of tumors in sharks.
Great white sharks do not mistake human divers for seals, nor other pinnipeds. When attacking pinnipeds, the shark surfaces quickly and attacks violently. In contrast, attacks on humans are slower and less violent: the shark charges at a normal pace, bites, and swims off. Great white sharks have efficient eyesight and color vision; the bite is not predatory, but rather for identification of an unfamiliar object.
Snake jaws cannot unhinge. The posterior end of the lower jaw bones contains a quadrate bone, allowing jaw extension. The anterior tips of the lower jaw bones are joined by a flexible ligament allowing them to bow outwards, increasing the mouth gape.
Tomato juice and tomato sauce are ineffective at neutralizing the odor of a skunk; it only appears to work due to olfactory fatigue. For dogs that get sprayed, The Humane Society of the United States recommends using a mixture of dilute hydrogen peroxide (3%), baking soda, and dishwashing liquid.
Porcupines do not shoot their quills. They can detach, and porcupines will deliberately back into attackers to impale them, but their quills do not project.
Mice do not have a special appetite for cheese, and will eat it only for lack of better options; they actually favor sweet, sugary foods. The myth may have come from the fact that before refrigeration, cheese was usually stored outside and was therefore an easy food for mice to reach.
There is no credible evidence that the candiru, a South American parasitic catfish, can swim up a human urethra if one urinates in the water in which it lives. The sole documented case of such an incident, written in 1997, has been heavily criticized upon peer review, and this phenomenon is now largely considered a myth.
Pacus, South American fish related to piranhas, do not attack or feed on human testicles. This myth originated from a misinterpreted joke in a 2013 report of a pacu being found in Øresund, the strait between Sweden and Denmark, which claimed that the fish ate "nuts".
Piranhas do not eat only meat but are omnivorous, and they only swim in schools to defend themselves from predators and not to attack. They very rarely attack humans, only when under stress and feeling threatened, and even then, bites typically only occur on hands and feet.
The hippopotamus does not produce pink milk. Hipposudoric acid, a red pigment found in hippo skin secretions, does not affect the color of their milk, which is white or beige.
The Pacific tree frog is the only frog species that makes a "ribbit" sound. The misconception that all frogs, or at least all those found in North America, make this sound comes from its extensive use in Hollywood films.
A human touching or handling eggs or baby birds will not cause the adult birds to abandon them. The same is generally true for other animals having their young touched by humans as well, with the possible exception of rabbits (as rabbits will sometimes abandon their nest after an event they perceive as traumatizing).
Rice does not cause birds to die by inflating their stomachs until they burst. Birds do eat wild rice, though some species avoid it. This common misconception has often led to weddings using millet, confetti, or other materials to shower the newlyweds as they leave the ceremony, instead of the throwing of rice that is traditional in some places.Brain
Broad generalizations are often made in popular psychology about certain brain functions being lateralized, or more predominant in one hemisphere than the other. These claims are often inaccurate or overstated.
The human brain, particularly the prefrontal cortex, does not reach "full maturity" at any particular age (e.g. 18, 21, or 25 years of age). Changes in structure and myelination of gray matter are recorded to continue with relative consistency all throughout adult life.  Some mental abilities peak and begin to decline around high school graduation while others do not peak until much later (i.e. 40s or later).
Humans do not generate all of the brain cells they will ever have by the age of two years. Although this belief was held by medical experts until 1998, it is now understood that new neurons can be created after infancy in some parts of the brain into late adulthood.
People do not use only 10% of their brains. While it is true that a small minority of neurons in the brain are actively firing at any one time, a healthy human will normally use most of their brain over the course of a day, and the inactive neurons are important as well. The idea that activating 100% of the brain would allow someone to achieve their maximum potential and/or gain various psychic abilities is common in folklore and fiction, but doing so in real life would likely result in a fatal seizure. This misconception was attributed to late 19th century leading thinker William James, who apparently used the expression only metaphorically.
Although Phineas Gage's brain injuries, caused by a several-foot-long tamping rod driven completely through his skull, caused him to become temporarily disabled, fanciful descriptions of his "immoral behavior" in later life are without factual basis.
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