irregardless
Regardless of how you feel about the matter, is it time to stop fretting about the use of irregardless? A reading of the OED would lead you to believe that this began life as a non-standard and dialectal item of American English, used more generally through the 20thcentury by those whose education was not quite up to scratch, and used mockingly and humorously by those whose education was vastly better. But, as I have said many times now, jokes in language are dangerous because eventually you arrive at a generation that doesn’t know the joke and takes the word for granted. Google ngram reveals a much more widespread use of irregardless in both British and American English through the 20th century, which peaks, interestingly, in the 1980s and then declines somewhat although it is obviously still well attested. I’m not sure what we did in the 1980s to stop the rot but it was only partially successful.
OED says that it is possibly a blend of irrespective and regardless but I don’t think it needs to have been derived from a conscious blend. Regardless could just have borrowed from the shape of irrespective, the irre- at the start of the word proving to be an irresistible model.