maternal uncle

eno; enopuoli mother's brother-in-law The brother or brother-in-law of one’s mother.
(quote-book)

The social organization of the Trobriand Islanders of Melane- sia is characterized by matrilineal descent, free and familiar rela- tions between father and son, and a marked antagonism between maternal uncle and nephew.31 On the other hand, the patrilineal Cherkess of the Caucasus place the hostility between father and son, while the maternal uncle assists his nephew and gives him a horse when he marries.32