Origin and history of anti-imperialist

c. 1600, "an adherent of an emperor or the imperial cause," such as the emperor of Germany (in the Thirty Years' War), France, China, etc., probably modeled on French impérialiste (early 16c.); from imperial + -ist. The shift in meaning to "advocate of imperialism" (1893) came via the British Empire, which involved a worldwide colonial system. See imperialism. As a term of abuse in communist circles, attested by 1918. As an adjective by 1816.

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).