regardless, irrespective, irregardless

Most dictionaries list irregardless as non-standard English and advise against its use in speech and writing. It is an illogical formation, since it contains a double negative: the negative prefix ir- (meaning “not”), combined with the negative suffix -less.

The correct word is regardless. The word irrespective is also correct and may replace regardless in the expression regardless of.

Use regardless as an adverb meaning “anyway” or “nonetheless”:

• The deadline seems unrealistic, but we’ll get the job done regardless (anyway).

Use regardless of or irrespective of as a preposition meaning “in spite of” or “without regard to”:

• Joe continued to sing regardless of (in spite of) the jeers and shouts from the audience.
• Candidates will be selected on merit, irrespective of (without regard to) their age or gender.