1. A vessel in which substances are crushed or ground with a pestle.
2. A machine in which materials are ground and blended or crushed.
3. 1. A portable, muzzleloading cannon used to fire shells at low velocities, short ranges, and high trajectories.
   2. Any of several similar devices, such as one that shoots life lines across a stretch of water.
4. Any of various bonding materials used in masonry, surfacing, and plastering, especially a plastic mixture of cement or lime, sand, and water that hardens in place and is used to bind together bricks or stones.

1. To bombard with mortar shells.
2. To plaster or join with mortar.

[Middle English morter, from Old English mortere and from Old French mortier, both from Latin mortārium.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.