Source : Webster's Revised Unabridged Dictionary (1913)

Labyrinthodon \Lab`y*rin"tho*don\, n. [Gr. laby`rinqos labyrinth
   + 'odoy`s, 'odo`ntos, tooth.] (Paleon.)
   A genus of very large fossil amphibians, of the Triassic
   period, having bony plates on the under side of the body. It
   is the type of the order Labyrinthodonta. Called also
   {{Mastodonsaurus}}.