Synonyms of oppositional

2 Syllables
anti, counter, battling, clashing, gainsaying, warring, denying, crossing, facing, rival
3 Syllables
adverse, contrary, hostile, opposed, averse, combating, conflicting, confronting, defending, disagreeing, disputed, disputing, exposing, dissentient, objecting, repelling, protesting, enemy, allergic
4 Syllables
controverting, antonymous, defensive, obstructive, restrictive, inimical, opposite, adversarial
5 Syllables
antagonistic, antithetical, antipathetic, incompatible
6 Syllables
irreconcilable