I note that the Merrion-Webster dictionary has included the word "irregardless" in its latest edition, defining it as a synonym for "regardless". According to The Times of India, this has caused an international outcry, because the word "irregardless" is wrong, a double negative – the prefix -ir is doing the same job as the suffix -less, and, if one takes a strictly logical view, the word ought to mean "not regardless". Merrion-Webster has defended the word's inclusion on the basis that its job is to record usage, not prescribe what's correct, and millions of people use "irregardless". The dictionary does make clear that it is a non-standard form. Its use was first recorded, apparently, in 1795.
Somewhat to my surprise, I find I don't have any strong feelings about this. Maybe that's because one hardly ever hears it in British English. It's an American form so I feel it's none of my business. When I hear the word in my head it's with an American accent (I imagine Abby Lee of Dance Moms saying it) and it sounds rather quaint.
I can see how it came about: -ir is used as a negative prefix in quite a few other cases ("irrelevant", "irrespective", "irreligious", etc.) and "irregardless" sounds like a natural member of that group. It has a more emphatic air than plain old "regardless". And longer words are always more fun to say. But I don't think I'll be saying it any time soon.
Dr Brandon Robshaw lectures for the Open University in Philosophy, Creative Writing and Children’s Literature. He has written several children’s books including a philosophical YA novel, The Infinite Powers of Adam Gowers. He and his family starred in BBC2’s Back in Time for Dinner. You can find his website here.