a prefix meaning “against,” “opposite of,” “antiparticle of,” used in the formation of compound words (anticline); used freely in combination with elements of any origin (antibody; antifreeze; antiknock; antilepton).
word-forming element meaning "against, opposed to, opposite of, instead," from Old French anti- and directly from Latin anti-, from Greek anti "against, opposite, instead of," also used as a prefix, from PIE *anti "against," also "in front of" (see ante). It appears in some words in Middle English but was not commonly used in word formations until modern times.
A prefix whose basic meaning is against. It is used to form adjectives that mean counteracting (such as antiseptic, preventing infection). It is also used to form nouns referring to substances that counteract other substances (such as antihistamine, a substance counteracting histamine), and nouns meaning something that displays opposite, reverse, or inverse characteristics of something else (such as anticyclone, a storm that circulates in the opposite direction from a cyclone). Before a vowel it becomes ant-, as in antacid.