The Collaborative International Dictionary of English v.0.48:
Patroness \Pa"tron*ess\, n. [Cf. F. patronnesse.] A female patron or helper. --Spenser. [1913 Webster] Night, best patroness of grief. --Milton. [1913 Webster]WordNet (r) 3.0 (2006):
patroness n 1: a woman who is a patron or the wife of a patron [syn: patroness, patronne]