Thank you! I never researched that specific word, and I thought it was a merge of 'irregard' and 'regardless' (at the semantic level of construction) which happ

Thank you! I never researched that specific word, and I thought it was a merge of 'irregard' and 'regardless' (at the semantic level of construction) which happened as the 'ir-' got used as an intensive prothesis (at the euphonic level), overriding its original negative sense. It seems like a case in which the prothesis is an effective intensifier, but compromised in the final logical flow of the word.