mortar UK /ˈmɔːtə/US /ˈmoɹtɚ/noun 5verb 4forms 3 noun5 •A mixture of lime or cement, sand and water used for bonding building blocks.The holy hearth! If any earthly and material thing, or rather a divine idea embodied in brick and mortar, might be supposed to possess the permanence of moral truth, it was this. — 1846 •A relatively lightweight, often portable indirect fire weapon which transmits recoil to a base plate and is designed to lob explosive shells at very steep trajectories. •(historical) A short, heavy, large-bore cannon designed for indirect fire at very steep trajectories. •A hollow vessel used to pound, crush, rub, grind or mix ingredients with a pestle. •In paper milling, a trough in which material is hammered. verb4 •To fire a mortar (weapon). •To attack (someone or something) using a mortar (weapon).The insurgents snuck up close and mortared the base last night. •To use mortar or plaster to join two things together. •To pound in a mortar. formsmortared · mortaring · mortars