Penthouse is a fine example of a word that has come about by the workings of folk etymology. Old French had the word apentis to denote ‘an outhouse projecting from the side of a main building’.The word was a borrowing of medieval Latin appendicium, ‘appendage’, a derivative of the Latin verb appendere (from ad-, ‘on’, and pendere, ‘to hang’) which meant ‘to attach, to suspend one thing from another’.When Middle English borrowed Old French apentis in the early fourteenth century, the initial vowel was dropped to give pentis.
There was immediate confusion over the word’s origins. Since most lean-tos are constructed with a sloping roof pentis was assumed to be a derivation of Middle French pente, meaning ‘slope’. By the sixteenth century pentis had also fallen prey to folk etymology, when the final syllable was changed to house, giving the compound penthouse. Penthouse continued to denote ‘a smaller structure attached to a main building’, with or without a sloping roof, down through the centuries.
An old nineteenth-century bill of sale for the Jolly Tanner public house in Staplefield, Sussex, lists stabling for 5 horses, a Blacksmith’s shop, Penthouse and Coal House amongst the outbuildings of that property. But this use has been eclipsed by a more recent application. Skyscrapers were originally intended to provide commercial accommodation in overcrowded American business quarters. However, as city populations grew, land became scarce and expensive city-wide creating a need to build vertically for domestic purposes also.
The term penthouse had already been applied to the rooftop housing of elevator shafts or stairwells – a small structure upon a large one. When it was understood that the rooftop area could provide a separate apartment affording a high degree of privacy together with spectacular views and a terrace, this extra dwelling built on the top of a high block became known as a penthouse. Two of the elevators were designed to run to the roof, where a pent-house .. . was being built, runs a description in Country Life magazine for April 1921, while on 8 December 1948 the New York Sun published a view of an eighteen-story and penthouse apartment building which was being erected at the south corner of Fifth Avenue and 76th Street.
More recenty, estate agents have begun to describe the top floor of any tall building as a penthouse so that the word no longer necessarily refers to an additional structure. True penthouses are highly sought after. An article in Good Housekeeping (March 1998) on the housing requirements of the rich and famous informs us that penthouses are popular simply because no one can overlook them – the actor Tom Cruise apparently can’t bear to have anyone in the room above!
Nice if you can afford it.