squirrel's cage

Noun

squirrel cage (plural squirrel cages)

1. A circular cage for a squirrel or other small animal, which rotates vertically as the animal runs at the bottom.

   Synonyms:

   squirrel wheel

2. (broadly, figuratively) A tedious, repetitive, unfulfilling activity or situation, especially one in which no progress is achieved.
   • The poor stuggle for riches, success, power; but those who achieve them die out. Life is, then a sort of squirrel cage or treadmill.1944, B. R. McElderry Jr., “The Grapes of Wrath: In the Light of Modern Critical Theory”, in College English, volume 5, number 6, page 312
3. Any other device, such as a fan or rotor, that resembles a squirrel cage in form.
   • A blower, in the shape of a drum fan (also called a "squirrel cage"), pulls the warm humid air from the room across the coils.1996 May 19, Edward R. Lipinski, “Home Clinic: Time to Inspect Air-Conditioners”, in New York Times, retrieved 13 Feb 2014