Meaning of quantum number

quan'tum num"ber

Pronunciation: [key]
— Physics. Physics.
  1. any integer or half of an odd integer that distinguishes one of the discrete states of a quantum-mechanical system.
  2. any number that distinguishes among different members of a family of elementary particles.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.