'mitey' is a playful variant of 'mighty', which originates from Old English 'mihtig', derived from 'miht' meaning 'power'.

'mihtig' evolved into Middle English 'mighty', and 'mitey' emerged as a playful variant in modern English.

Initially, 'mighty' meant 'having great power', and this meaning has largely remained the same, with 'mitey' being a playful variant.