A baby sheep is called a lamb, which is the most common and accurate term used to describe any sheep under a year old. However, there are other proper names for baby sheep, including ewe lamb for a young female sheep, ram lamb for a young male sheep, and wether for a young male sheep that has been castrated. In British English, a baby sheep can also be referred to as a lambkin. It is important to note that the term lamb is also used to describe the meat of any sheep under a year of age, which can sometimes cause confusion.