Source : Webster's Revised Unabridged Dictionary (1913)

Stenostome \Sten"o*stome\, a. [Gr. steno`s narrow, little +
   sto`ma mouth.] (Zo["o]l.)
   Having a small or narrow mouth; -- said of certain small
   ground snakes ({Opoterodonta}), which are unable to dilate
   their jaws.