hard hat (n.)youdaoicibaDictYouDict[hard hat 词源字典]
also hardhat, hard-hat, late 14c., "helmet," from hard (adj.) + hat (n.). From 1935 as "derby hat;" meaning "safety helmet" is from 1953; used figuratively for "construction worker" from 1970.[hard hat etymology, hard hat origin, 英语词源]