op·po·nent 
/əˈpoʊnənt/ noun
plural op·po·nents /əˈpoʊnənt/ noun [count] 1 : a person, team, group, etc., that is competing against another in a contest
▪ She is a formidable opponent in the race for senator. ▪ The team's opponents have not lost a game this season. ▪ He knocked out his opponent in the third round. 2 : a person, group, etc., that is against something (such as an action, law, or system) : someone or something that does not want something to exist, be done, etc. — often + of ▪ opponents of the war ▪ opponents of building a new baseball stadium ▪ opponents of abortion/slavery/communism — opposite proponent
▪ She is a formidable opponent in the race for senator. ▪ The team's opponents have not lost a game this season. ▪ He knocked out his opponent in the third round.
