'balanced-jawed' originates from Modern English, specifically a compound of 'balanced' and 'jawed', where 'balanced' is the past participle/adjective from 'balance' (ultimately from Old French via Latin roots referring to 'scales' or 'equilibrium') and 'jawed' is formed from the noun 'jaw' (a Germanic word) plus the adjectival/postpositional suffix '-ed' meaning 'having a jaw of a specified character'.

'balanced-jawed' developed in Modern English by combining the participial adjective 'balanced' with 'jaw' + '-ed'; such descriptive compounds have been used in anatomical and literary descriptions since the 18th–20th centuries and continue as a transparent compound in contemporary usage.

Initially it would have been a literal descriptive compound meaning 'having a balanced jaw'; over time its use has remained largely literal but broadened to describe overall facial proportion or aesthetic impression, not only strict anatomical balance.