early 14c., "body of men associated by common interest," from Old French fraternité (12c.), from Latin fraternitatem (nominative fraternitas) "brotherhood," from fraternus "brotherly," from frater "brother," from PIE root *bhrater- "brother." Meaning "state or condition of being as brothers" is from late 15c. College Greek-letter organization sense is from 1777, first in reference to Phi Beta Kappa.
1610s, "to sympathize as brothers," from French fraterniser, from Medieval Latin fraternizare, from Latin fraternus "brotherly" (see fraternity). Military sense of "cultivate friendship with enemy troops" is from 1897 (used in World War I with reference to the Christmas Truce). Used oddly in World War II armed forces jargon to mean "have sex with women from enemy countries" as a violation of military discipline.
A piece of frat, Wren-language for any attractive young woman — ex-enemy — in occupied territory. [John Irving, "Royal Navalese," 1946]
Related: Fraternized; fraternizing.
bhrāter-, Proto-Indo-European root meaning "brother."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhrátár-, Old Persian brata, Greek phratér, Latin frater, Old Irish brathir, Welsh brawd, Lithuanian broterėlis, Old Prussian brati, Old Church Slavonic bratru, Czech bratr, Polish brat, Russian bratŭ, Kurdish bera; Old English broþor, Old Norse broðir, German Bruder, Gothic bróþar.
"convent of friars, monastery," 1530s, from French, from Old French frarie, from Medieval Latin fratria "a fraternity," from frater "brother" (from PIE root *bhrater- "brother").
mid-14c., pinnen, "to affix with a pin," from pin (n.). Figurative uses, on the notion of "seize and hold fast in the same spot or position" are from 1570s. Related: Pinned; pinning. Sense of "to hold someone or something down so he or it cannot escape" is attested from 1740. In U.S. colleges, as a reference to the bestowal of a fraternity pin on a female student as an indication of a relationship, it is attested by 1938. Phrase pin down "define" is from 1951.
mid-14c. (implied in rushing), "to drive back or down," from Anglo-French russher, from Old French ruser "to dodge, repel," which is from Latin recusare"make an objection against; decline, refuse, reject; be reluctant to" (see recuse; also compare ruse).
The meaning "do something quickly" is from 1650s, hence "to move or act with undue eagerness or without deliberation or preparation;" the transitive sense of "to hurry up (someone or something), cause to go swiftly" is from 1850. The sporting sense in U.S. football originally was in rugby (1857).
The fraternity/sorority sense is by 1896 (originally it was what the fraternity did to the student); from 1899 as a noun in this sense, "entertainment for prospective pledges." Earlier it was a name on U.S. campuses for tests of strength or athletic skill between freshmen and sophomores as classes (1860).
drug slang, "to keep a joint in your mouth," dangling from the lip like Humphrey Bogart's cigarette in the old movies, instead of passing it on, by 1968, in "Don't Bogart That Joint" by Fraternity of Man. The word also was used 1960s with notions of "get something by intimidation, be a tough guy" (again with reference to the actor and the characters he typically played). In old drinking slang, Captain Cork was "a man slow in passing the bottle."