(pronounced like the initials: see-em-yu)

This abbreviation stands for concrete masonry unit, otherwise known as cement block, concrete block, or foundation block. Manufactured from cast concrete, these large, heavy, and rectangular bricks are prevalently used in construction due to their relatively low cost, durability, and maintainability. When reinforced with rebar, CMU can be used for load-bearing walls, and it is installed with grout like other types of masonry.