ne·ol·o·gism /nēˈäləˌjizəm/ Learn to pronounce noun noun: neologism ; plural noun: neologisms a newly coined word or expression. Similar: new word new expression new term new phrase coinage newly coined word made-up word invented word invention nonce word portmanteau word the coining or use of new words. Origin early 19th century: from French néologisme . Courtesy Of Google Dictionary