: related through the mother <maternal grandparents>
Word Root of MATERNAL
The Latin word mater, meaning “mother,” gives us the root mater or matr. Anyone or anything maternal, such as a grandparent, is related through the mother's side of the family. Maternity is the state of being a mother. A matriarch is a woman who is the mother and head of a family. A matron is a married woman who may be a mother.
Medical Definition of MATERNAL
: of, relating to, belonging to, or characteristic of a mother <maternal instinct>
a: related through a mother <his maternal aunt>b: inherited or derived from the female parent <maternal genes>