merry-go-round

Short definition from Wiktionary

Noun

1. 1
   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.
2. 2
   A piece of playground equipment consisting of a circular platform that is made to revolve by pushing while users stand on it.
3. 3
   A meaningless cycle; a bustle of activity that gets nowhere.
4. 4
   A freight train of hopper wagons which loads and unloads its cargo while moving, a balloon loop being provided at power stations.
5. 5
   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.
6. 6
   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.