What is "mortar vessel"

Bomb \Bomb\, n. [F. bombe bombshell, fr. L. bombus a humming or buzzing noise, Gr. ?.]

1. A great noise; a hollow sound. [Obs.]

   A pillar of iron . . . which if you had struck, would make . . . a great bomb in the chamber beneath.
   --Bacon.

2. (Mil.) A shell; esp. a spherical shell, like those fired from mortars. See Shell.

3. A bomb ketch.

   Bomb chest (Mil.), a chest filled with bombs, or only with gunpowder, placed under ground, to cause destruction by its explosion.

   Bomb ketch, Bomb vessel (Naut.), a small ketch or vessel, very strongly built, on which mortars are mounted to be used in naval bombardments; -- called also mortar vessel.

   Bomb lance, a lance or harpoon with an explosive head, used in whale fishing.

   Volcanic bomb, a mass of lava of a spherical or pear shape. ``I noticed volcanic bombs.''
   --Darwin.