antonym
Concise Oxford English Dictionary © 2008 Oxford University Press:
antonym /ˈantənɪm/
▶noun a word opposite in meaning to another.
– derivatives
antonymous /anˈtɒnɪməs/ adjective,
antonymy /anˈtɒnɪmi/ noun.
antonymous /anˈtɒnɪməs/ adjective,
antonymy /anˈtɒnɪmi/ noun.
– origin C19: from Fr. antonyme, from ant- (from Gk anti- ‘against’) + Gk onoma ‘a name’.
'antonym' also found in these Oxford entries:

