The definition of an opponent is someone who you compete against, who has interests opposing yours, or is a person who is against something.(noun)
See opponent in Webster's New World College Dictionary
Origin: < L opponens, prp. of opponere < ob- (see ob-) + ponere, to place: see position
See opponent in American Heritage Dictionary 4
Origin: Latin oppōnēns, oppōnent-
Origin: , present participle of oppōnere, to oppose; see oppose.
Learn more about opponent