The sheep (Ovis aries) is a quadrupedal, ruminant mammal typically kept as livestock. Like most ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Although the name “sheep” applies to many species in the genus Ovis, in everyday usage it almost always refers to Ovis aries. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. An adult female sheep is referred to as a ewe, an intact male as a ram or occasionally a tup, a castrated male as a wether, and a younger sheep as a lamb. [Credit: Wikipedia]