1 : of or relating to a father

• He did not neglect his paternal responsibilities after the divorce.
• He offered them some paternal [=fatherly] advice.

2 always used before a noun : related through the father

• his paternal grandparents [=the parents of his father]
• a paternal aunt/uncle

— paternally adverb

• He smiled at them paternally.
• paternally inherited genes