An uncle is a name used in an extended family. An uncle is either a brother of one of someone's parents or the husband of their aunt. That person is the uncle's nephew (male) or niece (female). An uncle's child is a cousin. A granduncle (also written as great-uncle or grand-uncle) is the brother or brother-in-law of a grandparent. In some cultures an uncle is considered a close family member. Based on the old Chinese saying "the oldest son in the family is the father of the family" an uncle is often the head of a family. In many cultures no single word (such as uncle) describes both their parents' brothers. Instead there are words to describe a person's kinship to their mother's brother or a person's kinship to their father's brother. An uncle can also be someone not related by blood or marriage as in a term of endearment or respect. In this use uncle can also be part of a nickname such as Uncle Sam.
During the Middle Ages in western Europe, a maternal uncle played a particular role in the family. A young man was often closer to his maternal uncle (from Latin: avunculus or "little grandfather") than to his own father. Tacitus noted the Franks had very strong ties between a maternal uncle and his nephew. In Roman family relationships the avunculus had a responsibility to defend his nephews as well as his nieces. The maternal uncle relationship was an extension of the Roman kin system's strong brother-sister relationship.
- The Utah Genealogical and Historical Magazine; Volumes 7-9, Vol. vii, ed. Anthon Henrik Lund (Salt Lake City, UT: The Genealogical Society of Utah, 1916), p. 179
- Sonia M. Chen, China Changing in My Eyes: People, Schools and Landscapes (Bloomington, IN: Authorhouse, 2010), p. 49
- Thomas Montgomery, Medieval Spanish Epic (University Park, PA: The Pennsylvania State University Press, 1998), p. 67
- David Herlihy, Medieval Households (Cambridge, MA: Harvard University Press, 1985), p. 54
- Growing Up Fatherless in Antiquity, eds. Sabine R. Hübner; David M. Ratzan (Cambridge; New York: Cambridge University Press, 2009), 227