antibody n.

word-forming element of Greek origin meaning "against, opposed to, opposite of, instead," shortened to ant- before vowels and -h-, from Old French anti- and directly from Latin anti-, from Greek anti (prep.) "over, against, opposite; instead, in the place of; as good as; at the price of; for the sake of; compared with; in opposition to; in return; counter-," from PIE *anti "against," also "in front of, before" (from root *ant- "front, forehead," with derivatives meaning "in front of, before"), which became anti- in Italian (hence antipasto) and French.

It is cognate with Sanskrit anti "over, against," and Old English and- (the first element in answer). A common compounding element in Greek, in some combinations it became anth- for euphonic reasons. It appears in some words in Middle English but was not commonly used in English word formations until modern times. In a few English words (anticipate, antique) it represents Latin ante.

In noun compounds where it has the sense of "opposed to, opposite" (Antichrist, anti-communist) the accent remains on the anti-; in adjectives where it retains its old prepositional sense "against, opposed to," the accent remains on the other element (anti-Christian, anti-slavery).

Middle English bodi, from Old English bodig "trunk of a man or beast; the whole physical structure of a human or animal; material frame, material existence of a human; main or principal part of anything," related to Old High German botah, but otherwise of unknown origin. Not elsewhere in Germanic, and the word has died out in German (replaced by Leib, originally "life," and Körper, from Latin), "but in English body remains as a great and important word" [OED].

The extension to "a person, a human being" is by c. 1300. The meaning "main part" of anything was in late Old English, hence its use in reference to vehicles (1520s). From 1580s as "part of the dress which covers the body."

It is attested from 1590s as "main part of a group, any number of individuals spoken of collectively" and from 1660s as "main portion of a document." Contrasted with soul at least since mid-13c. The meaning "corpse" ("dead body") is from c. 1200. The word was transferred to matter generally in Middle English (as in heavenly body, late 14c.).

Body politic "the nation, the state, whole body of people living under an organized government" is recorded from late 15c., with French word order. Body image was coined 1934. Body count "number of enemy killed in battle or otherwise" is from 1968, from the Vietnam War. Body language is attested from 1967, perhaps from French langage corporel (1966). Body-snatcher "one who secretly disinters the bodies of the recently dead for dissection" is from 1834. Defiant phrase over my dead body attested by 1833.

"substance that causes production of an antibody," 1908, from German Antigen, from French antigène (1899), from anti(body) (see antibody) + -gen.