graybeard (n.)youdaoicibaDictYouDict[graybeard 词源字典]
also greybeard, "old man," 1570s, from gray (adj.) + beard (n.). Middle English had gray-hair (n.) "old man" (late 15c.), and simple gray in this sense is from late 14c.[graybeard etymology, graybeard origin, 英语词源]