1. A vessel in which substances can be ground with a pestle.
2. Used as a bond in masonry or for covering a wall.

A muzzle-loading cannon with a short barrel that fires shells at high elevations for a short range; SYN. howitzer, trench mortar.
Method of projecting a bomb via a high trajectory at a target up to 6–7 km/3–4 mi away. A mortar bomb is stabilized in flight by means of tail fins. The high trajectory results in a high angle of attack and makes mortars more suitable than artillery for use in built-up areas or mountains; mortars are not as accurate, however. Artillery also differs in firing a projectile through a rifled barrel, thus creating greater muzzle velocity.
Mortars began to be developed when the trench lines came into use in World War I, so that missiles could be pitched into the enemy trenches. The German minenwerfer was an early and complex design, but the archetypal early mortar was the British Stokes design 1915. This was a simple tube with a fixed firing pin at the bottom end, into which a bomb carrying a blank shotgun cartridge and some smokeless powder was dropped. The cartridge hit the pin, ignited the powder, and blew the bomb from the barrel.

To plaster with mortar.