synonym
Concise Oxford English Dictionary © 2008 Oxford University Press:
synonym /ˈsɪnənɪm/
▶noun a word or phrase that means the same as another word or phrase in the same language, e.g. shut and close.
– derivatives
synonymic adjective,
synonymity noun,
synonymy /sɪˈnɒnɪmi/ noun.
synonymic adjective,
synonymity noun,
synonymy /sɪˈnɒnɪmi/ noun.
– origin ME: via L. from Gk sunōnumon, neut. of the adj. sunōnumos, from sun- ‘with’ + onoma ‘name’.
'synonym' also found in these Oxford entries:

