Wiktionary
n. One of the pieces of meat initially separated from the carcass during butchering.
Wikipedia
A primal cut or cut of meat is a piece of meat initially separated from the carcass of an animal during butchering. Examples of primals include the beef round, loin, rib, and chuck or the swine ham, loin, Boston butt, and picnic.
Different countries and cultures make these cuts in different ways, and primal cuts also differ between type of carcass. The British, American and French primal cuts all differ in some respects. For example, "rump steak" in British and Commonwealth English is commonly called "sirloin" in American English. On the other hand, British "sirloin" is called "porterhouse" by Americans. Another notable example is fatback, which in Europe is an important primal cut of pork, but in North America is regarded as trimmings to be used in sausage or rendered into lard. The primal cuts may be sold complete or cut further.
The distinct term "prime cut" is sometimes used to describe cuts considered to be of better quality; for example in the US Department of Agriculture meat grading systems, most use "prime" to indicate top quality.