IrregardlessWhy you should avoid using "irregardless"
Even though irregardless is commonly used in informal English, even by some educated people, it is considered a nonstandard word; since –less is a negative suffix, the negative prefix ir- is redundant. Use regardless instead.
Irregardless Regardless of my warnings, he insisted on rushing forward into battle, shouting “Leeeeeerooooy Jeeeenkins!”
Although some traditional rules of usage are obsolete, arbitrary, and not worth trying to save, this is one that I think is worth following: it’s logical, the word regardless is more concise and conveys the same meaning, and most educated writers know and follow it.
Common Errors in English Usage: Errors in diction and idiom commonly made by native speakers of English
List of Common Errors in English Usage (PDF): Printable version of the complete list
Common Grammar Errors: A list of common errors in grammar (topics like subject-verb agreement and parallelism) as distinct from usage