According to Sheep 101, an adult male sheep has several names, including ram or buck. A young sheep under the age of 1 is a ram lamb. In the United Kingdom, a male sheep is called a tup.
Castrated bucks are referred to as wethers. Sheep between the ages of 1 and 2 are considered yearlings. A group of three or more sheep is a flock, and larger flocks are bands or mobs. Shortly after birth, lambs are able to stand. Sheep have few defenses against their natural predators of coyotes and wild dogs. They eat by grazing, and a specialized split lip helps them easily select the leaves from their favorite plants.