noun
or tour·bil·lon tu̇rˈbilyən, tu̇əˈ-
( -s )
Etymology: Middle French tourbillon whirl, vortex, whirlwind, from Latin turbin-, turbo — more at turbine
1. : something that whirls around or moves spirally: as
a. : whirlwind
b. : a vortex especially of a whirlwind or whirlpool
c. : a firework having a spiral flight
2. : a watch in which the escapement is mounted on an epicyclic train and assumes all the vertical positions in one minute thereby neutralizing the position errors
3. : the whirl of the hair near the vertex of the human head