tourbillon

noun

1. A rotating frame, containing the escapement of a clock or watch, that attempts to compensate for the effects of gravity.

   “Time was vulnerable to the force of gravity. So Breguet came up with the tourbillon, which isolated the balance wheel and escarpment off on a little platform of their own, geared to the third wheel, rotating about once a minute, assuming in the course of the day most positions in 3-D space relative to the gravity of the Earth, so the errors would cancel out and make time impervious to gravity.”

   “In their final year, each student must make their own watch with a complication—from a tourbillon to a chiming mode to having a date display.”

2. A whirlwind.
3. A kind of firework that gyrates in the air.
4. Any part of a machine with a spiral movement.