An enemy.
Of a hostile takeover.
Aggressive; antagonistic.
Not friendly; appropriate to an enemy; showing the disposition of an enemy; showing ill will and malevolence or a desire to thwart and injure.
Unwilling.
A side, party (e.g. a team or armed force) seen as adversary, enemy etc. opposite one (or more) other(s), as in a battle or team sports competition.