Webster's 1913 Dictionary
ANTITHETICALLY
ANTITHETICALLY An `ti *thet "ic *al *ly, adv.
Defn: By way antithesis.
New American Oxford Dictionary
antithetical
an ti thet i cal |ˌantəˈTHetikəl ˈˌæn (t )əˈθɛdəkəl | ▶adjective 1 directly opposed or contrasted; mutually incompatible: people whose religious beliefs are antithetical to mine | two antithetical emotions pulled at her. 2 [ attrib. ] connected with, containing, or using the rhetorical device of antithesis. DERIVATIVES an ti thet ic adjective, an ti thet i cal ly adverb ORIGIN late 16th cent. ( sense 2 ): from Greek antithetikos, from antithetos ‘placed in opposition, ’ from antitithenai ‘set against. ’
Oxford Dictionary
antithetical
antithetical |ˌantɪˈθɛtɪk (ə )l | ▶adjective 1 directly opposed or contrasted; mutually incompatible: people whose religious beliefs are antithetical to mine. 2 connected with, containing, or using the rhetorical device of antithesis. DERIVATIVES antithetic adjective, antithetically adverb ORIGIN late 16th cent. (in sense 2 ): from Greek antithetikos, from antithetos ‘placed in opposition ’, from antitithenai ‘set against ’.
American Oxford Thesaurus
antithetical
antithetical adjective your theories are antithetical to mine: (directly ) opposed to, contrasting with, contrary to, contradictory to, conflicting with, incompatible with, irreconcilable with, inconsistent with, at variance with, at odds with. ANTONYMS identical, like. CHOOSE THE RIGHT WORD See opposite . These notes show fine distinctions in meaning between closely related synonyms to help you find the best word.
Oxford Thesaurus
antithetical
antithetical adjective an administration packed with people holding policy views antithetical to his own: (directly ) opposed to, contrary to, contradictory to, conflicting with, incompatible with, irreconcilable with, inconsistent with, at variance with, at odds with, contrasting with, different from /to, differing from, divergent from, unlike; opposing, poles apart, polar, obverse; rare oppugnant. ANTONYMS same, identical, like.