Lamb, hogget, and mutton, generically sheep meat, are the meat of domestic sheep, Ovis aries. A sheep in its first year is a lamb and its meat is also lamb. The meat from sheep in their second year is hogget. Older sheep meat is mutton. Generally, "hogget" and "sheep meat" are not used by consumers outside Norway, New Zealand, South Africa, Scotland, and Australia. Hogget has become more common in England, particularly in the North (Lancashire and Yorkshire) often in association with rare breed and organic farming.

In South Asian and Caribbean cuisine, "mutton" often means goat meat. At various times and places, "mutton" or "goat mutton" has occasionally been used to mean goat meat.

Lamb is the most expensive of the three types and in recent decades sheep meat is increasingly only retailed as "lamb", sometimes stretching the accepted distinctions given above. The stronger-tasting mutton is now hard to find in many areas, despite the efforts of the Mutton Renaissance Campaign in the UK. In Australia, the term prime lamb is often used to refer to lambs raised for meat. Other languages, such as French, Spanish, Italian, and Arabic, make similar or even more detailed distinctions among sheep meats by age and sometimes by sex and diet—for example, lechazo in Spanish refers to meat from milk-fed (unweaned) lambs.