Different cultures name their kin in different ways. For example, in the Coos languages there are different terms for older sister versus younger, and older brother versus younger; whereas English simply uses the term ‘sister’ or ‘brother’ (or ‘sibling’) without regard to birth order. Also, where English uses the term ‘aunt’ for the sister of either one’s mother or father the Coos languages have different terms for maternal aunts versus paternal ones – same for uncles.
One of the muddy areas of Hanis kinship terms has been ‘nephew’. Usually the term duuwidech (deu in vocative form) was used for nephew. But the word k’ilmiya’wach (also recorded k’ilniya’wach) was defined as nephew or niece and also as a euphemistic address for sea serpent. So now there are two words for nephew, and only one also applied to sea serpents. What was going on here?
Well, going through Frachtenberg’s Coos Grammatical Notes 1, he defined k’ilmiya’wach (or, kîlîmiyáKatc as he wrote it there) as the ‘son & daughter of my brother-in-law’. Perhaps duuwidech by contrast referred to the children of one’s brother and sister-in-law.