1. The avunculate, sometimes called avunculism or avuncularism, is any social institution where a special relationship exists between an uncle and his sisters' children. This relationship can be formal or informal, depending on the society. Early anthropological research focused on the association between the avunculate and matrilineal descent, while later research has expanded to consider the avunculate in general society. == Definition == The term avunculate comes from the Latin avunculus, the maternal uncle. The 1989 Oxford English Dictionary defines "avunculate" as follows: "Avunculate. The special relationship existing in some societies between a maternal uncle and his sister's son; maternal uncles regarded as a collective body. 1920 R. H. LOWIE Prim. Soc. v. 81 Ethnologists describe under the heading of avunculate the customs regulating in an altogether special way the relations of a nephew to his maternal uncle. Ibid. vii. 171 The Omaha are patrilineal now, but their having the avunculate... from wikipedia.org