From Latin 'mederi' (to heal), from PIE *med- (to measure) — connecting healing to measurement and moderation.
The science or practice of diagnosing, treating, and preventing disease; also, a substance used in treatment.
From Old French 'medecine,' from Latin 'medicīna' (the healing art, a remedy, a drug), from 'medicus' (a physician, a healer), from 'medērī' (to heal, to attend to, to remedy), from PIE *med- (to take appropriate measures, to measure out, to give counsel). The PIE root *med- encodes a profound idea: healing is fundamentally an act of measurement and judgment — the physician assesses, weighs, and applies the appropriate measure. The same root produced Latin 'modus' (measure, manner, method), 'modesty' (keeping