1.Definition: a contestant that you are matched against

Related Noun(s):opponent, opposition

Category: People

2.Definition: a relation of direct opposition

Related Noun(s):contrary, reverse

Category: General

3.Definition: a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other

Related Noun(s):antonym

Category: General

4.Definition: something inverted in sequence or character or effect

Related Noun(s):inverse

Category: General