mortar boat

from The Collaborative International Dictionary of English v.0.48
Mortar \Mor"tar\, n. [OE. morter, AS. mort[=e]re, L. mortarium:
   cf. F. mortier mortar. Cf. sense 2 (below), also 2d {Mortar},
   {Martel}, {Morter}.]
   1. A strong vessel, commonly in form of an inverted bell, in
      which substances are pounded or rubbed with a pestle.
      [1913 Webster]

   2. [F. mortier, fr. L. mortarium mortar (for trituarating).]
      (Mil.) A short piece of ordnance, used for throwing bombs,
      carcasses, shells, etc., at high angles of elevation, as
      45[deg], and even higher; -- so named from its resemblance
      in shape to the utensil above described.
      [1913 Webster]

   {Mortar bed} (Mil.), a framework of wood and iron, suitably
      hollowed out to receive the breech and trunnions of a
      mortar.

   {Mortar boat} or {Mortar vessel} (Naut.), a boat strongly
      built and adapted to carrying a mortar or mortars for
      bombarding; a bomb ketch.

   {Mortar piece}, a mortar. [Obs.] --Shak.
      [1913 Webster]
    

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