'unequal-jawed' originates from Modern English, specifically formed by compounding 'unequal' and 'jawed'; 'unequal' ultimately comes from Old French/Latin ('inegal', from Latin 'inaequalis') where 'in-' meant 'not' and 'aequalis' meant 'equal', and 'jaw' comes from Old English roots referring to the mouth bone.

'unequal' passed into Middle English from Old French/Latin ('inaequalis' → Old French 'inegal' → Middle English 'unequal'), and 'jaw' was the established Old English word for the mouth bone that developed into the Middle English 'jaw', with the modern compound 'unequal-jawed' forming in Modern English by simple combination.

Initially, the elements meant 'not equal' (unequal) and 'jaw/bone of the mouth' (jaw). Over time they combined to form the descriptive compound meaning 'having uneven or asymmetrical jaws'.