[ an-tuh-nim ]
/ ˈæn tə nɪm /


a word opposite in meaning to another. Fast is an antonym of slow.Compare synonym(def 1).

Origin of antonym

First recorded in 1865–70; ant- + (syn)onym


an·ton·y·mous [an-ton-uh-muh s] /ænˈtɒn ə məs/, an·to·nym·ic, adjectivean·ton·y·my, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for antonym

  • By and by, which was once a synonym, has become an antonym of immediately, meaning at some (perhaps remote) future time.

    English Synonyms and Antonyms|James Champlin Fernald
  • In strict usage, daily is the antonym of nightly as diurnal is of nocturnal.

    English Synonyms and Antonyms|James Champlin Fernald

British Dictionary definitions for antonym

/ (ˈæntənɪm) /


a word that means the opposite of another word``empty'' is an antonym of ``full''

Derived forms of antonym

antonymous (ænˈtɒnɪməs), adjective

Word Origin for antonym

C19: from Greek antōnumia, from anti- + onoma name
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012