opponent
1. op.po.nent \*-'po--n*nt\ n [L opponent-, opponens, prp. of opponere] 1: one that opposes : ADVERSARY 2: a muscle that opposes or counteracts and limits the action of another e than position on the other side as in a debate, election, contest, or conflict; ANTAGONIST implies sharper opposition in a struggle for supremacy; ADVERSARY may carry an additional implication of active hostility SYN syn ANTAGONIST, ADVERSARY: OPPONENT implies little mor 2. opponent aj 1: OPPOSING, ANTAGONISTIC 2: situated in front : OPPOSITE
Webster's English Dictionary