Usage Note: Irregardless is a word that many people mistakenly believe to be correct in formal style, when in fact it is used chiefly in nonstandard speech or casual writing. The word was coined in the United States in the early 1900s, presumably from a blend of irrespective and regardless. Many critics have complained that it is a redundancy, the negative prefix ir- duplicating the negativity of the -less suffix. Perhaps its reputation as a blend of ill-fitting parts has caused some to insist that it is a "nonword," a charge they would not think of leveling at a nonstandard word with a longer history, such as ain't. Since people use irregardless, it is undoubtedly a word in the broader sense of the language, but it has never been accepted in Standard English and is virtually always changed by copyeditors to regardless. The Usage Panel has roundly disapproved of its use since polling began; in 2012, 90 percent found the sentence A scientist investigating a social issue should seek to find out the truth, irregardless of its political implications to be unacceptable.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.