• (n.) An ornamental firework which turns round, when in the air, so as to form a scroll of fire.
Tour·bil'lion noun [ French torbillion a whirlwind, tourbillion, from Latin turbo , - inis , a whirl, whirlwind.] An ornamental firework which turns round, when in the air, so as to form a scroll of fire. G. Francis. 
A tourbillion or 'Catherine Wheel' is a type of firework so constructed as to rotate in flight forming spiral curves. The firework is mounted to a stake by a pin through its center and spins when ignited.
A complication in mechanical watches that eliminates any error in timekeeping that might be cause by shifts in location due to variations in gravity