Synonyms of opposing

2 Syllables
agin, anti, against, naysaying, coner, rival
3 Syllables
adverse, opposed, resisting, conflicting, confronting, dissentient, resistant, contrariant, contending
4 Syllables
negative, antonymic, privative, antonymous, defensive, recalcitrant, antithetic, antipodean, opposite
5 Syllables
antagonistic, competitive, unsupportive, contradictory
6 Syllables
unaffirmative