Pauli principle

This term refers to a specific law of quantum physics and is used almost exclusively within scientific, academic, and technical registers. It is a proper noun phrase named after physicist Wolfgang Pauli, and as such, the word Pauli is always capitalized.

Because it describes a singular, universal law of nature, the term is treated as a unique entity. It does not typically appear in plural form, as there is only one Pauli exclusion principle governing the behavior of fermions.