merry-go-round

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A revolving circular platform fitted with seats, often in the form of animals, ridden for amusement.
• noun A piece of playground equipment consisting of a small circular platform that revolves when pushed or pedaled.
• noun A busy round; a whirl.

from The Century Dictionary.

• noun A revolving machine, consisting of a series of wooden horses or carriage-seats, mounted on a circular platform, on or in which children and sometimes grown persons ride for amusement. In the United States also called a carrousel.

from the GNU version of the Collaborative International Dictionary of English.

• noun Any revolving contrivance for affording amusement; esp., a group of seats in the shape of hobbyhorses or other fanciful animals, arranged in a circle on a platform that is rotated by a mechanical drive, often to the accompaniment of music; the seats often move up and down in synchrony with the rotation; -- called also carousel. It is employed primarily for the amusement of children, and is typically found at an amusement park.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun carousel; a pleasure ride consisting of a slowly revolving circular platform affixed with various types of seats, frequently horses or other animals, typically found at fairs and amusement parks
• noun a piece of playground equipment in the style of a merry-go-round
• noun figuratively A dead-end search; a bustle of activity that gets nowhere

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a never-ending cycle of activities and events (especially when they seem to have little purpose)
• noun a large, rotating machine with seats for children to ride or amusement