Wiktionary
alt. (context mathematics physics English) A linear operator that makes a wave function of ''N'' identical fermions antisymmetric under the exchange of the coordinates of any pair of fermions. n. (context mathematics physics English) A linear operator that makes a wave function of ''N'' identical fermions antisymmetric under the exchange of the coordinates of any pair of fermions.
Wikipedia
In quantum mechanics, an antisymmetrizer A (also known as antisymmetrizing operator ) is a linear operator that makes a wave function of N identical fermions antisymmetric under the exchange of the coordinates of any pair of fermions. After application of A the wave function satisfies the Pauli principle. Since A is a projection operator, application of the antisymmetrizer to a wave function that is already totally antisymmetric has no effect, acting as the identity operator.