variant of in-2 (by assimilation) before r: irradiate.
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.” …
Definition for ir- (2 of 2)
variant of in-3 (by assimilation) before r: irreducible.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for ir-
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