a word coined and used only for a particular occasion.Compare neologism(def 1).
Is Irregardless A Word?Few words draw the ire of grammarians as swiftly as irregardless. The term has been in use in English for over a century, but whether or not it’s a “real word” or one you should use in daily conversation continues to be the subject of debate. Irregardless is a nonstandard synonym for regardless, which means “without concern as to advice, warning, or hardship,” or “heedless.” …
Origin of nonce word
First recorded in 1880–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for nonce word
a word coined for a single occasion
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