The word "maternal" refers to a mother and the word "paternal" refers to a father. Specifically, maternal describes a characteristic that pertains to being a mother and paternal describes a characteristic that pertains to being a father.
The word "maternal" is first attested in Middle English between 1475 and 1485, entering the language from the medieval Latin "māternālis." The word "paternal" entered the English language between 1400 and 1450 and is derived from the late Latin " paternālis." Both of these words are still widely used today, often when discussing relatives. For example, a paternal grandmother is a grandmother on the father's side of the family.