n (grammar) In some languages, one of several classifications of verbs according to what inflections they take.
n (chemistry) A system of delocalized orbitals consisting of alternating single|single bonds and double bonds
n (mathematics) A mapping sending x to gxg-1, where g and x are elements of a (l|en|group); (l|en|inner automorphism)
n (mathematics) A function which negates the non-real part of a (l|en|complex) or (l|en|hypercomplex) number; (l|en|complex conjugation)