Definition: (adjective) More than is needed, desired, or required.
Synonyms: excess, extra, redundant, supererogatory, surplus, superfluous, spare.
Usage: His appearance…is apt to occasion some little stir at the tea-table of a farmhouse, and the addition of a supernumerary dish of cakes or sweetmeats, or, peradventure, the parade of a silver teapot.
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Source: The Free Dictionary