helmetyoudaoicibaDictYouDict[helmet 词源字典]
helmet: [15] A helmet is literally a ‘little protective hat’. The word was borrowed from Old French helmet, a diminutive form of helme ‘helmet’. This in turn was acquired by Old French from Germanic *khelmaz (source of English helm [OE]), which goes back ultimately to Indo-European *kel- ‘hide, cover’ (source of a wide range of English words, including apocalypse, cell, cellar, conceal, hall, hell, and occult).
=> hell, helm[helmet etymology, helmet origin, 英语词源]
helmet (n.)youdaoicibaDictYouDict
mid-15c., perhaps a diminutive of Old English helm "protection, covering; crown, helmet" (see helm (n.2)). But Barnhart says from Middle French helmet (Modern French heaume), diminutive of helme "helmet," from the same Germanic source as helm (n.2). "Middle English Dictionary" points to both without making a choice. "Old English helm never became an active term in the standard vocabulary of English." [Barnhart]