From Old French formatif, formative, from Medieval Latin formātīvus, from Latin fōrmātus + -īvus (suffix forming adjectives with the sense ‘doing’ or ‘related to doing’). Fōrmātus is the perfect passive participle of fōrmō (“to form, to shape”); further etymology uncertain, possibly related to Ancient Greek μορφή (morphḗ, “a form, shape”) (see further at that entry). By surface analysis, former + -atif.