opposition; contrast: the antithesis of right and wrong.
2.
the direct opposite (usually fol. by of or to): Her behavior was the very antithesis of cowardly.
3.
Rhetoric.
a.
the placing of a sentence or one of its parts against another to which it is opposed to form a balanced contrast of ideas, as in “Give me liberty or give me death.”
b.
the second sentence or part thus set in opposition, as “or give me death.”
1529, from L.L. antithesis, from Gk. antithesis "opposition," lit. "a placing against," noun of action from antitithenai "to set against, oppose," a term in logic, from anti- "against" + tithenai "to place," from PIE base *dhe- "to put, to do" (see factitious).