Either the thymus gland or the pancreas, the former being called neck sweetbread or throat sweetbread, the latter belly sweetbread. The sweetbreads of ruminants, esp. of the calf, are highly esteemed as food. See Pancreas, and Thymus.
The culinary term for the thymus gland of an animal. Those of veal and lamb are most commonly eaten. The pancreas is also considered a sweetbread, but its taste and texture is inferior to that of the thymus gland.
Sweetbread is the name of a dish made of the thymus (neck/throat/gullet sweetbread) or the pancreas (belly/stomach/heart sweetbread) of an animal younger than one year old. These animals are usually lamb(IMH)s or calves.