irregardless is mentioned in some reference books but it's an example of ignorance becoming the norm, not adoption from another language or created like "to google" or "xerox" and if you have a fondness for the English language you would abhor its use.
In most references it carries a notation as in "use regardless or irrespective instead"
Of course language evolves and new words come into existence all the time but I cannot think of another word that has come into use in a similar way. Maybe I will get plenty :)
