'crooked' originates from Old English and Old Norse influences, specifically the Old English/Old Norse root 'crōc'/'krókr', where 'crōc'/'krókr' meant 'hook'.

'crooked' changed from Old English forms such as 'crōc'/'crocc' (related to a hook or bent shape) and Old Norse 'krókr' and eventually became the modern English adjective 'crooked', with the adverb formed by adding '-ly'.

Initially it meant 'bent like a hook' or 'hooked' (a physical shape), but over time it developed the additional figurative meaning of 'dishonest' or 'deceitful', leading to the modern senses 'not straight' and 'dishonestly' and then the adverb 'crookedly'.