/ ˈpenthaʊs; NAmE / noun
an expensive and comfortable flat / apartment or set of rooms at the top of a tall building
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WORD ORIGIN
Middle English pentis (originally referring to an outhouse or shelter with sloping roof), shortening of Old French apentis , based on late Latin appendicium appendage, from Latin appendere hang on. The change of form in the 16th cent. was by association with French pente slope and house .