exclusion principle: Meaning and Definition of

exclu'sion prin"ciple

Pronunciation: [key]
— Physics. Physics.
  1. the principle that in any system described by quantum mechanics no two identical particles having spin equal to half an odd integer can be in the same quantum state: first postulated for the electrons in atoms. Also calledCf. fermion.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.