As nouns, upstairs and downstairs are surprisingly recent additions to the language. Upstairs isn’t recorded in English until 1842 (in a novel called Handy Andy by one Samuel Lover), and downstairs is first seen the following year in a letter written by Jane Carlyle. In both cases, the context makes clear that the words were already in existence— Jane Carlyle was no coiner of terms— but no earlier written records have yet been found. The upshot is that for at least three centuries people lived on multiple ?oors, yet had no convenient way of expressing it.
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