diverticulum

from WordNet (r) 3.0 (2006)

diverticulum
    n 1: a herniation through the muscular wall of a tubular organ
         (especially the colon)

from The Collaborative International Dictionary of English v.0.48

Diverticulum \Div`er*tic"u*lum\, n.; pl. {Diverticula}. [L. See
   {Diverticle}.] (Anat.)
   A blind tube branching out of a longer one.
   [1913 Webster]