Source : Webster's Revised Unabridged Dictionary (1913)

Anti \An"ti\ [Gr. ? against. See {Ante}.]
   A prefix meaning against, opposite or opposed to, contrary,
   or in place of; -- used in composition in many English words.
   It is often shortened to ant-; as, antacid, antarctic.

Source : WordNet®

anti
     adj : not in favor of (an action or proposal etc.) [ant: {pro}]