Middle English pentis (in sense 2), shortening of Old French apentis, based on late Latin appendicium 'appendage', from Latin appendere 'hang on'. The change of form in the 16th century was by association with French pente 'slope' and house.

• A penthouse now suggests a luxurious apartment with extensive views, but originally was much more humble—a shed, outhouse, or lean-to attached to the outside of a building, and called a pentis. The word came from a shortening of French apentis, which is from Latin pendere ‘to hang’, the source of appendage, appendix, and pendant. In the 16th century people began to forget its origins and to associate it with French pente ‘slope’ and house. The modern use for a flat or apartment on the top floor of a tall building began during the 1890s in the USA. At first these penthouses were not necessarily exclusive—the first reference to one talks of it as accommodation for a janitor and his family.