Definition of the word cinder block

The word "cinder block" originated in the early 20th century during the Industrial Revolution when coal was extensively used as a fuel source. Coal burning in factories and power plants generated a large amount of coal ash, which included small pieces of hardened coal known as "cinders." These cinders were initially thrown out as waste, but some ingenious individuals discovered that they could be molded into blocks for building purposes. The first known use of cinder blocks as building materials was in the late 1800s in the UK. Initially, the blocks were made by mixing cinders with clay and water and forming it into blocks using hydraulic presses. This process was repeated in the US, where the resulting blocks came to be known as "concrete cinder blocks" due to their increased durability over regular clay bricks. By the 1920s and 30s, cinder block became increasingly popular in construction due to its affordability, strength, and fire resistance properties. Today, cinder blocks are still widely used in construction and are known as "concrete masonry units" (CMUs) or just plain "concrete blocks."