Harl is a Scottish term for a type of roughcast plaster used to cover exterior walls. It is sometimes also known as pebbledash. Synonyms for harl might include stucco, render, or plaster. Stucco is a term more commonly used in America and refers to a type of exterior plaster that is typically composed of Portland cement, sand, and water. Render is a term that originates from England and is used to describe a similar type of exterior plaster made from lime, sand, and water. Plaster is a more general term that encompasses a wide range of building materials used for interior and exterior finishes.