English to English

noun (n)

• a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other(noun.communication)

  Example:
  To him the antonym of `gay' was `depressed'.
  

  Synonym:
  opposite, opposite word
  Antonym:
  equivalent word, synonym
  

  source: wordnet30
• A word of opposite meaning; a counterterm; -- used as a correlative of synonym.(noun)

  source: webster1913