What is the meaning of Merry-go-round?

A carousel; a pleasure ride, typically found at fairs and amusement parks, consisting of a slowly revolving circular platform on which various seats are fixed, frequently shaped like horses or other animals.

A piece of playground equipment consisting of a circular platform that is made to revolve by pushing while users stand on it.

A meaningless cycle; a bustle of activity that gets nowhere

A freight train of hopper wagons which loads and unloads its cargo while moving, a balloon loop being provided at power stations.

A series of singles and doubles that allow the batting team to score while still having runners on base who can be driven in by the next batter.

A cooperative scheme in which members regularly contribute money to a pool, and the collected money is then paid out to one of the members, repeating so that every member has eventually received the collected money.

Source: wiktionary.org