anti- Syllabification: (anti-) (also ant-)Translate anti- | into German | into Spanish Definition of anti- prefix opposed to; against:antiaircraft preventing or suppressing:antibacterial reversing or undoing:anticoagulant antigravity antipruritic the opposite of:anticlimax Physics the opposite state of matter or of a specified particle:antimatter antiproton acting as a rival:antipope unlike the conventional form:antiheroOrigin:representing Greek anti 'against'anti- in other Oxford dictionaries Definition of anti- in the British & World English dictionary