The Pauli exclusion principle is the quantum mechanical principle that says that two identical fermions (particles with half-integer spin) cannot occupy the same quantum state simultaneously. In the case of electrons, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum...
assertion that no two electrons in an atom can be at the same time in the same state or configuration, proposed (1925) by the Austrian physicist ... [20 related articles]
states that no two electrons may have the same quantum numbers. Only two electrons may occupy an orbital, but they must have opposite spins.
No two electrons in the same atom may have identical sets of four quantum numbers.
A fundamental rule in subatomic physics which states that no two electrons, or other types of fermion, can occupy the same quantum state at the same place and time; it was formulated by the German physicist Wolfgang Pauli in 1925. The exclusion principle, for example, prevents white dwarfs that are ...
No two electrons in the same atom may have identical sets of four quantum numbers.
Fermions obey a rule called the Pauli Exclusion Principle, which states that no two fermions can exist in the same state at the same time. 
Type: Term Pronunciation: paw′lē Definitions: 1. the theory limiting the number of electrons in the orbit or shell of an atom; that it is not possible for any two electrons to have all four quantum numbers identical.
[n] - no two electrons or protons or neutrons in a given system can be in states characterized by the same set of quantum numbers
exclusion principle noun no two electrons or protons or neutrons in a given system can be in states characterized by the same set of quantum numbers
No two fermions of the same type can exist in the same state at the same place and time.