What is the name of a sheep that has not had babies?

A sheep that has not had babies is called a ewe lamb or simply a lamb.

Here's why:

* Ewe: A female sheep.

* Lamb: A young sheep, regardless of sex.

* Ewe lamb: Specifically refers to a young female sheep that has not yet given birth.

So, while "lamb" is technically correct, "ewe lamb" is more specific and indicates that the sheep is a female and hasn't had babies yet.