"aged woman," 1580; earlier "grandmother" (c.1440), from
dame (q.v.) in the sense of "mother" +
bel-, M.E. prefix expressing relationship (cf.
belfader, belsire "grandfather"), from O.Fr.
bel, belle "beautiful, fair, fine." This "direct relationship" sense of
bel is not found in Fr., where the prefix is used to form words for in-laws.