tussock (n.)youdaoicibaDictYouDict[tussock 词源字典]
1540s, "tuft of hair," of uncertain origin; perhaps a diminutive of earlier tusk (1520s) with the same meaning (and also of obscure origin). Meaning "tuft of grass" is first recorded c. 1600.[tussock etymology, tussock origin, 英语词源]