The term for a young sheep between weaning and first shearing is hogget.
A hogget is generally a sheep in the stage after it has stopped relying on its mother’s milk but before it receives its first adult shearing. The term can apply to either sex, although regional farming vocabulary varies. In some places, a hogget may also be described by age, often around 9–18 months.
“Hogget” is not the same as lamb, which usually refers to a younger sheep. A wether is a castrated male sheep, while an ewe is an adult female; neither word describes this particular age-and-shearing stage. After its first shearing, the animal may be called a shearling or classified by its teeth and age.
The word also appears in sheep-meat terminology. Hogget meat comes from older animals than lamb and usually has a deeper flavor and firmer texture. Exact age boundaries differ between countries, but the weaning-to-first-shearing definition is the standard distinction relevant to this question.