[Rathji]

Originally Posted by Barnes

1. Yes, it is. http://dictionary.reference.com/search?q=irregardless

ir⋅re⋅gard⋅less [ir-i-gahrd-lis] Show IPA Pronunciation
–adverb Nonstandard. regardless.

Origin:
1910–15; ir- 2 (prob. after irrespective) + regardless
Dictionary.com Unabridged (v 1.1) - Cite This Source

Am I missing something or is the source for this online dictionary the online dictionary itself? As is no real dictionary has this included?