Real Dictionary

mortar
countable noun: A mortar is a big gun which fires missiles high into the air over a short distance.

mortar in American English
a very hard bowl in which softer substances are ground or pounded to a powder with a pestle
to plaster or bind together with mortar

mortar in American English 1
to attack with mortar fire or shells
noun: a receptacle of hard material, having a bowl-shaped cavity in which substances are reduced to powder with a pestle

mortar in American English 2
noun: a mixture of lime or cement or a combination of both with sand and water, used as a bonding agent between bricks, stones, etc
transitive verb: to plaster or fix with mortar

mortar in British English
to join (bricks or stones) or cover (a wall) with mortar
noun: a mixture of cement or lime or both with sand and water, used as a bond between bricks or stones or as a covering on a wall