The domestic sheep (Ovis aries) (plural domestic sheep), the most common species of the sheep genus (Ovis), is a woolly ruminant quadruped. It is probably descended from the wild mouflon of South Asia and Southwest Asia.
Sheep breeders refer to female sheep as ewes, intact males as rams, castrated males as wethers, yearlings as hoggets, and younger sheep as lambs. In sheep husbandry, a group of sheep is called a herd, flock or mob. See other specialised vocabulary below.
The sheep is closely related to the goat, both being in the goat antelope subfamily Caprinae, itself part of the family Bovidae. However, sheep and goats differ genetically so greatly that cross-species hybrids do not occur.