Is it ensure, insure, or assure?
until recently a difficult word to trace, in part because it was taboo to the editors of the original OED when the "F" volume was compiled, 1893-97. Written form only attested from early 16c. OED 2nd edition cites 1503, in the form fukkit; earliest appearance of current spelling is 1535 -- "Bischops ... may fuck thair fill and be vnmaryit" [Sir David Lyndesay, "Ane Satyre of the Thrie Estaits"], but presumably it is a much more ancient word than that, simply one that wasn't written in the kind of texts that have survived from Old English and Middle English. Buck cites proper name John le Fucker from 1278, but the surname could have other explanations. The word apparently is hinted at in a scurrilous 15c. poem, titled "Flen flyys," written in bastard Latin and Middle English. The relevant line reads:
Non sunt in celi"They [the monks] are not in heaven because they fuck the wives of [the town of] Ely." Fuccant is pseudo-Latin, and in the original it is written in cipher. The earliest examples of the word otherwise are from Scottish, which suggests a Scandinavian origin, perhaps from a word akin to Norwegian dialectal fukka "copulate," or Swedish dialectal focka "copulate, strike, push," and fock "penis." Another theory traces it to Middle English fyke, fike "move restlessly, fidget," which also meant "dally, flirt," and probably is from a general North Sea Germanic word; cf. Middle Dutch fokken, German ficken "fuck," earlier "make quick movements to and fro, flick," still earlier "itch, scratch;" the vulgar sense attested from 16c. This would parallel in sense the usual Middle English slang term for "have sexual intercourse," swive, from Old English swifan "to move lightly over, sweep" (see swivel). But OED remarks these "cannot be shown to be related" to the English word. Chronology and phonology rule out Shipley's attempt to derive it from Middle English firk "to press hard, beat."
quia fuccant uuiuys of heli
Germanic words of similar form (f + vowel + consonant) and meaning 'copulate' are numerous. One of them is G. ficken. They often have additional senses, especially 'cheat,' but their basic meaning is 'move back and forth.' ... Most probably, fuck is a borrowing from Low German and has no cognates outside Germanic. [Liberman]French foutre and Italian fottere look like the English word but are unrelated, derived rather from Latin futuere, which is perhaps from PIE root *bhau(t)- "knock, strike off," extended via a figurative use "from the sexual application of violent action" [Shipley; cf. the sexual slang use of bang, etc.]. Popular and Internet derivations from acronyms (and the "pluck yew" fable) are merely ingenious trifling. The Old English word was hæman, from ham "dwelling, home," with a sense of "take home, co-habit." Fuck was outlawed in print in England (by the Obscene Publications Act, 1857) and the U.S. (by the Comstock Act, 1873). As a noun, it dates from 1670s. The word may have been shunned in print, but it continued in conversation, especially among soldiers during World War I.
It became so common that an effective way for the soldier to express this emotion was to omit this word. Thus if a sergeant said, 'Get your ----ing rifles!' it was understood as a matter of routine. But if he said 'Get your rifles!' there was an immediate implication of urgency and danger. [John Brophy, "Songs and Slang of the British Soldier: 1914-1918," pub. 1930]The legal barriers broke down in the 20th century, with the "Ulysses" decision (U.S., 1933) and "Lady Chatterley's Lover" (U.S., 1959; U.K., 1960). Johnson excluded the word, and fuck wasn't in a single English language dictionary from 1795 to 1965. "The Penguin Dictionary" broke the taboo in the latter year. Houghton Mifflin followed, in 1969, with "The American Heritage Dictionary," but it also published a "Clean Green" edition without the word, to assure itself access to the lucrative public high school market.
DUCK F-CK-R. The man who has the care of the poultry on board a ſhip of war. ["Classical Dictionary of the Vulgar Tongue," 1796]
An exclamation of disgust, disappointment, dismay, etc: and yelled against the moan of the wind as loud as he could, ''Fuck!'' (1940s+)noun
[origin unknown; perhaps fr or related to German ficken, ''strike, copulate with'']