a word (as ringday in "four girls I know have become engaged today: this must be ringday") coined and used apparently to suit one particular occasion sometimes independently by different writers or speakers but not adopted into use generally <Coleridge coined mammonolatry in 1820 as a nonce word> <I still think I heard it, though so seldom that it had more or less the air of a nonce word -- S.T.Byington>
- Webster's Third New International Dictionary, Unabridged. Merriam-Webster (W3)