Adobe, Spanish word for a sun-dried brick and for the clay soil from which the brick is made. Adobe soils are found in many arid and semiarid regions worldwide, notably in North Africa, Mexico, and the southwestern United States. In the western United States, adobe soils cover thousands of square miles. Adobe has been used for thousands of years to build houses and other structures. For example, ancient Babylonians, ancient Egyptians, and some Native American cultures of North and South America used adobe.