From Latin 'mortarium' (mixing bowl) — the paste named for its vessel; the cannon later named for its bowl-like shape.
A mixture of lime, cement, sand, and water used to bind bricks or stones in construction; also a bowl in which substances are ground with a pestle, and a short-barreled artillery piece.
From Old French 'mortier,' from Latin 'mortārium' (mortar, a vessel for mixing or pounding). The Latin word originally denoted the mixing bowl — the container in which ingredients were ground together with a pestle. The building material was named by extension: mortar is the 'stuff mixed in a mortar.' The artillery piece (a short cannon