"a buffoon; a zany; a jack-pudding" [Johnson], originally "mountebank's assistant," 1670s, from merry + masc. proper name Andrew, but there is no certain identification with an individual.
merrily
merriment
merry
merry man
Merry Widow
merry-andrew
merry-go-round
merrymaking
merrythought
mesa
mesalliance
