A nonstandard dialect form of 'himself,' used in some regional varieties of English.
From 'his' plus 'self.' This form developed naturally from speech patterns but is considered grammatically incorrect in standard English. It reflects historical pronunciation and dialect evolution.
Hisself is completely logical grammar—if we have 'herself' (her-self), why not 'hisself'? It reveals that 'himself' is actually the irregular one. Dialects keep making language more logical, even when standard grammar says no.
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