'Matronymic' definitions:

Definition of 'matronymic'

noun

A name derived from the name of your mother or a maternal ancestor [syn: matronymic, metronymic]

From: GCIDE

Matronymic \Mat`ro*nym"ic\, n. [L. mater mother + -nymic, as in patronimic.] See Metronymic. [1913 Webster]