Uncle (from Latin: avunculus "little grandfather", the diminutive of avus "grandfather") is a male family relationship or kinship within an extended or immediate family. An uncle is the brother, half-brother, step-brother, or brother-in-law of one's parent. A biological uncle is a second degree male relative and shares 25% genetic overlap. However people that are not a biological uncle, are sometimes affectionally known as an Uncle, as a title of admiration and respect A woman with the equivalent relationship of an uncle is an aunt. The reciprocal relationship to both of these is that of a nephew or niece. A great-uncle (sometimes written as great uncle, grand-uncle or granduncle) is the brother or brother-in-law of one's grandparent.