FLOOR (from O. Eng. flor, a word common to many Teutonic languages, cf. Dutch vloer, and Ger. Flur, a field, in the feminine, and a floor, masculine), generally the lower horizontal surface of a room, but specially employed for one covered with boarding or parquetry. The various levels of rooms in a house are designated as "ground-floor," "first-floor," "mezzanine-floor," etc. The principal floor is the storey which contains the chief apartments whether on the ground- or first-floor; in Italy they are always on the latter and known as the "piano nobile." The storey below the ground-floor is called the "basement-floor," even if only a little below the level of the pavement outside; the storey in a roof is known as the "attic-floor." The expressions one pair, two pair, etc., apply to the storeys above the first flight of stairs from the ground (see also Carpentry).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)