Antagonistic, Antagonistical, a.
Opposing in combat, combating; contending or acting against; as, antagonistic forces. -- An*tag`o*nis"tic*al*ly, adv. They were distinct, adverse, even antagonistic. Milman.
Shades of meaning
Fernald lists antagonistic only as an antonym, under friendly, propitious.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given