The male children of one's siblings. Nephew is also a traditional term of formal endearment, one that signifies the relationship of affinity and mentorship that exists between an elder and a younger male member of the Navajo community.
"An old Navajo brave and his nephew, both huddled in their blankets, circa 1901" by Charles C.
A04 Dancehall of the Dead (02-04) p. 11
Tony Hillerman Portal