From Frankish *helm (protective covering), from PIE *ḱel- (to cover) — kin to 'conceal,' 'hell,' 'cell,' and 'apocalypse.'
A hard or padded protective hat worn to protect the head.
From Old French 'helmet' (mid-15th century), a diminutive of 'helme' (helmet, protective headgear), itself borrowed from Frankish *helm (protective covering for the head), from Proto-Germanic *helmaz (protective covering, helmet), from PIE *ḱel- (to cover, to conceal, to hide, to save). The word is thus a Germanic root that traveled into French during the Frankish period and returned to English with a French diminutive suffix — a round trip across the Channel. The earlier English form 'helm' came directly from Old English 'helm' (helmet,
The name 'Wilhelm' (and its English form 'William') contains the 'helm' root: it comes from Old High German 'willo' (will, desire) + 'helm' (protection). A Wilhelm is a 'resolute protector.' The helmets of medieval Germanic warriors were so culturally significant that 'helm' became one of the most common elements in personal names across all Germanic languages.