Source : Webster's Revised Unabridged Dictionary (1913)

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

Source : WordNet®

matronymic
     n : a name derived from the name of your mother or a maternal
         ancestor [syn: {metronymic}]