n. [ OE. foil leaf, OF. foil, fuil, fueil, foille, fueille, F. feuille, fr. L. folium, pl. folia; akin to Gr. &unr_; , and perh. to E. blade. Cf. Foliage, Folio. ] 1. A leaf or very thin sheet of metal; as, brass foil; tin foil; gold foil. [ 1913 Webster ] 2. (Jewelry) A thin leaf of sheet copper silvered and burnished, and afterwards coated with transparent colors mixed with isinglass; -- employed by jewelers to give color or brilliancy to pastes and inferior stones. Ure. [ 1913 Webster ] 3. Anything that serves by contrast of color or quality to adorn or set off another thing to advantage. [ 1913 Webster ] As she a black silk cap on him began
To set, for foil of his milk-white to serve. Sir P. Sidney. [ 1913 Webster ] Hector has a foil to set him off. Broome. [ 1913 Webster ] 4. A thin coat of tin, with quicksilver, laid on the back of a looking-glass, to cause reflection. [ 1913 Webster ] 5. (Arch.) The space between the cusps in Gothic architecture; a rounded or leaflike ornament, in windows, niches, etc. A group of foils is called trefoil, quatrefoil, quinquefoil, etc., according to the number of arcs of which it is composed. [ 1913 Webster ]
Foil stone, an imitation of a jewel or precious stone. [ 1913 Webster ]
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