the compound adjective 'strong-willed' is a relatively modern english formation, combining two native germanic elements. the first element, 'strong', descends from old english 'strang', meaning physically powerful or forceful, itself from proto-germanic 'strangaz'. the second element, 'willed', is derived from the noun 'will', from old english 'will(a)', meaning desire, intention, or the faculty of volition, traceable to proto-germanic 'wiljô'. the '-ed' suffix here functions to create a participial adjective meaning 'having a will'. the compound thus literally means 'having a powerful or forceful will', a transparent metaphor where mental determination is conceptualized as a form of strength, directly linking the ancient concepts of physical power and volition to the modern psychological trait of resoluteness.

Structure: strong (powerful) + willed (possessing a will) strong (old english, meaning 'powerful, forceful'); willed (old english-derived, from 'will' meaning 'desire, intention', with the suffix '-ed' indicating 'possessing the quality of').