'anisognathousness' originates from Greek elements: 'aniso-' (from Greek 'anisos') meaning 'unequal' and 'gnathos' meaning 'jaw', combined with the English nominal suffix '-ness'.

'anisognathousness' was formed in modern scientific English by combining Greek roots (aniso- + gnathos) into the adjective 'anisognathous' and then adding the English suffix '-ness' to create the noun; it entered usage via New Latin/scientific coinage rather than through a single intermediate medieval form.

Initially formed to denote the literal condition 'unequal jaws', and this technical meaning has been preserved in modern usage.