African-American vernacular, "white person," 1925, of unknown origin. If, as is sometimes claimed, it derives from an African word, none corresponding to it has been found. Perhaps the most plausible speculation is Yoruba ófé "to disappear" (as from a powerful enemy), with the sense transferred from the word of self-protection to the source of the threat. OED regards the main alternative theory, that it is pig Latin for foe, to be no more than an "implausible guess." Sometimes shortened to fay (1927).
mid-14c., offertorie, "antiphon said or sung after the Credo during the part of a Mass at which offerings are made," from Medieval Latin offertorium "place where offerings are brought," from Vulgar Latin offertus, corresponding to Latin oblatus, past participle of offerre (see offer (v.)). Meaning "part of a religious service beginning with an offering" is first recorded 1530s; sense of "the collection of money received as offerings" is from 1862. Related: Offertorial.
slang, "perform male masturbation," by 1896, from jerk (v.) denoting rapid pulling motion + off (adv.). Compare come off "experience orgasm" (17c.). Farmer and Henley ("Slang and Its Analogues") also lists as synonyms jerk (one's) jelly and jerk (one's) juice. The noun jerk off or jerkoff as an emphatic form of jerk (n.2) is attested by 1968. As an adjective from 1957.