“Irregardless” is not a word. I don’t care what people say, or how many times I hear it (like nails on a chalkboard), it will never become a proper word. If you look “irregardless” up in the dictionary, it’s called nonstandard and colloquial. It actually dates back to the early 20th century, with a link to colloquialisms in Indiana (USA). Recently (early 21st century) it has begun to get more and more use. IT’S STILL WRONG!
Let’s take it apart. To “regard” something is to give it merit, to take it into account. If I hold something in “high regard” I feel very strongly about it, and I respect it. “Regardless” means that you do not give something merit. It is not something that matters in the conversation, or in your thought process. To put the prefix “ir” in front of “regardless” actually makes it a double negative…which, in turn, makes it positive. So, “irregardless” is actually saying that you don’t disregard something. So, in actuality, you give it merit and it matters greatly. Do you see the idiocy behind this word?! So, when people use “irregardless” in conversation to mean that something doesn’t matter, what they’re actually saying is that it matters a great deal. So “irregardless of your feelings” actually means “taking your feelings into account.”
Etymologists believe that the word is a bastardized portmanteau form of the words “regardless” and “irrespective,” which fundamentally mean the same thing. But, when you combine the two, the meaning changes completely. Some people will say “this is the evolution of language, and this is how languages are born.” Well, there’s bad words (anyways), which weasel their way into everyday conversation that could one day become regularly used, and there’s bad grammar (irregardless), which will always be bad grammar!
“Irregardless” gained popularity in the early 2000s when the likes of Lacey Chabert and Jamie Pressley used in their movies Mean Girls and Not Another Teen Movie. Just like the sheep that everyone is, people started using the word (first mockingly, and then for real) because it was used in popular media at the time. Well, it’s wrong! It’s not a proper word, and it’s a double negative anyway. Even the Merriam-Webster dictionary (which hales it as a colloquialism or nonstandard word) says “use regardless instead!!” (http://www.merriam-webster.com/dictionary/irregardless)