beldam (n.)youdaoicibaDictYouDict[beldam 词源字典]
"aged woman," 1570s; earlier "grandmother" (mid-15c.), from dame (q.v.) in the sense of "mother" + bel-, Middle English prefix expressing relationship (as in belfader, belsire "grandfather"), from Old French bel, belle "beautiful, fair, fine" (see belle). This "direct relationship" sense of bel is not found in French, where the prefix is used to form words for in-laws.[beldam etymology, beldam origin, 英语词源]