labyrinthodon, n. [Gr. laby`rinthos labyrinth + 'odoy`s, 'odo`ntos, tooth.].
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. [1913 Webster]