mat·ro·nym·ic 
(m
ăt
′r
ə-n
ĭm
ĭk) also
me·tro·nym·ic (m
ē′tr
ə-, m
ĕt
′r
ə-)
adj. Of, relating to, or derived from the name of one's mother or maternal ancestor.
[Greek mātrōnumikos, dialectal variant of mētrōnumikos : mētēr, mētr-, mother; see METRO- + onuma, name; see n-men- in the Appendix of Indo-European roots.]