hard-headed (adj.)youdaoicibaDictYouDict[hard-headed 词源字典]
also hardheaded, 1580s, "stubborn," from hardhead "dull person" (1510s), from hard (adj.) + head (n.). Meaning "practical, shrewd" is attested from 1779. Compare Dutch hardhoofdig "stupid."[hard-headed etymology, hard-headed origin, 英语词源]