This article compounds the effort of a social anthropologist and a linguist to understand and to analyze what is known about the triadic terms of the Mẽbêngôkre, a Northern Jê people from Central Brazil. Triadic terms are kinship terms that refer to a single individual but encode at least two kin relations simultaneously: that between the addressee and the referent, and that between the speaker and the referent; their meaning can be represented schematically as “your X = [who is also] my Y.” The only other region where this phenomenon has been identified so far is among the First Peoples of Northern Australia. Our aim is to describe the logic of this system of terminology, and to examine the social variables governing its use.