Source : Webster's Revised Unabridged Dictionary (1913)

Pirouette \Pir`ou*ette"\, n. [F.; of uncertain origin.]
   1. A whirling or turning on the toes in dancing.

   2. (Man.) The whirling about of a horse.

Pirouette \Pir`ou*ette"\, v. i. [imp. & p. p. {Pirouetted}; p.
   pr. & vb. n. {Pirouetting}.] [F. pirouetter.]
   To perform a pirouette; to whirl, like a dancer.

Source : WordNet®

pirouette
     n : (ballet) a rapid spin of the body (especially on the toes as
         in ballet)
     v : do a pirouette, usually as part of a dance