Sheep, ruminant (cud-chewing) mammal of the genus Ovis. The sheep is usually stockier than its relative the goat; its horns, when present, are more divergent; it has scent glands in its face and hind feet; and the males lack the beards of goats. Sheep usually have short tails. In all wild species of sheep, the outer coat takes the form of hair, and beneath this lies a short undercoat of fine wool that has been developed into the fleece of domesticated sheep. Male sheep are called rams, the females ewes, and immature animals; lambs. Mature sheep weigh from about 80 to as much as 400 pounds.