Also called carousel, carrousel. (in amusement parks, carnivals, etc.) a revolving, circular platform with wooden horses or other animals, benches, etc., on which people may sit or ride, usually to the accompaniment of mechanical or recorded music.
a rapid whirl or a busy round, as of social life or business affairs.
1729, from merry (adj.) + go (v.) + round. Figurative use by 1838. Merry-totter (mid-15c.) was a Middle English name for a swing or see-saw. Also cf. merry-go-down "strong ale" (c.1500); merry-go-sorry "a mix of joy and sorrow" (1590s).