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.
against, opposed to anti-government
Prefix generally meaning "against, opposite or opposing, and contrary." In medicine, anti- often connotes "counteracting or effective against" as in antibacterial, anti-infective, and antiviral. Sometimes medical terms containing anti- take on new meanings as has occurred with antibiotic and antibody. As a prefix, anti- may be shortened to ant- as in antacid. "Anti" is the Greek word for "against." See the entire definition of Anti
(prefix) against; counteracting. e.g. antitoxin - an antibody to a toxin.