"of the nature of or containing a (rhetorical) antithesis," 1580s, from Greek antithetikos "setting in opposition," from antithetos "placed in opposition," from antithesis "opposition, resistance," literally "a placing against" (see antithesis) + -al (1). General sense of "characterized by direct opposition" is from 1848. Related: Antithetically.
practices entirely antithetical to her professed beliefs
antitheism
antitheist
antitheses
antithesis
antithetic
antithetical
antitoxic
antitoxin
anti-trust
antitype
antivenin