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,
1. A strong vessel, commonly in form of an inverted bell, in
which substances are pounded or rubbed with a pestle.
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.
Mortar bed (Mil.), a framework of wood and iron, suitably
hollowed out to receive the breech and trunnions of a
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.