Source : Webster's Revised Unabridged Dictionary (1913)

Sweetbread \Sweet"bread`\, n.
   1. Either the thymus gland or the pancreas, the former being
      called {neck, or throat, sweetbread}, the latter {belly
      sweetbread}. The sweetbreads of ruminants, esp. of the
      calf, are highly esteemed as food. See {Pancreas}, and
      {Thymus}.

   2. (Anat.) The pancreas.