Agnate

Part of speech: noun (n.)

A relative whose relationship can be traced exclusively through males.

Part of speech: adjective (a.)

1. Related or akin by the father's side; also, sprung from the same male ancestor.

2. Allied; akin. "Agnate words." Pownall. Assume more or less of a fictitious character, but congenial and agnate with the former. Landor.