Irregardless of what anyone may say to the contrary, "irregardless" is not a word.

This paradoxical¹ sentence contains an error in diction and a fundamental concept that may help you answer questions on standardized examinations and improve your speech and writing.

As the main clause of the sentence explains, "irregardless" is not a word in standard American English. While it may be encountered in colloquial speech, its use should be avoided in formal speech and writing.

This nonstandard word may have developed as a combination of "regardless," which means "without concern (for); without consideration (of)," and "irrespective," which means "independent (of); regardless." These two synonyms are words, but "irregardless" is not. [Note: this type of word combination is known as a "portmanteau."]

¹The word "paradoxical" is the adjective form of "paradox." A paradox is something that has contradicting qualities. A paradox may be a statement that seems to be contradictory or unbelievable but that may actually be true, or it may be a contradictory person or thing.

A statement that is commonly used as an example of a paradox is "This sentence is false." If the sentence is true, then it is false.