uncle

An uncle is usually defined as a male relative who is a sibling of a parent or married to a sibling of a parent, as well as the parent of the cousins. Uncles who are related by birth are second-degree relatives. The female counterpart of an uncle is an aunt, and the reciprocal relationship is that of a nephew or niece. The word comes from Latin: avunculus, the diminutive of avus (grandfather), and is a family relationship within an extended or immediate family.

In some cultures and families, children may refer to the cousins of their parents as uncle (or aunt). It is also used as a title of respect for older relatives, neighbours, acquaintances, family friends, and even total strangers in some cultures, for example Aboriginal Australian elders. Using the term in this way is a form of fictive kinship.
Any social institution where a special relationship exists between a man and his sisters' children is known as an avunculate (or avunculism or avuncularism). 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.

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