ANTITHETIC
antithetic, antithetical
(adjective) sharply contrasted in character or purpose; “practices entirely antithetical to her professed beliefs”; “hope is antithetic to despair”
Source: WordNet® 3.1
Adjective
antithetic (comparative more antithetic, superlative most antithetic)
diametrically opposed
antithetical
Source: Wiktionary
An`ti*thet"ic, An`ti*thet"ic*al, a. Etym: [Gr.
Definition: Pertaining to antithesis, or opposition of words and
sentiments; containing, or of the nature of, antithesis; contrasted.
Source: Webster’s Unabridged Dictionary 1913 Edition