Source : Webster's Revised Unabridged Dictionary (1913)

Thymus \Thy"mus\, a. [NL., fr. Gr. qy`mos.] (Anat.)
   Of, pertaining to, or designating, the thymus gland. -- n.
   The thymus gland.

   {Thymus gland}, or {Thymus body}, a ductless gland in the
      throat, or in the neighboring region, of nearly all
      vertebrates. In man and other mammals it is the throat, or
      neck, sweetbread, which lies in the upper part of the
      thorax and lower part of the throat. It is largest in
      fetal and early life, and disappears or becomes
      rudimentary in the adult.

Source : WordNet®

thymus gland
     n : a ductless glandular organ at the base of the neck that
         produces lymphocytes and aids in producing immunity;
         atrophies with age [syn: {thymus}]