Definition of foil

• v. t. - To tread under foot; to trample.
• v. t. - To render (an effort or attempt) vain or nugatory; to baffle; to outwit; to balk; to frustrate; to defeat.
• v. t. - To blunt; to dull; to spoil; as, to foil the scent in chase.
• v. t. - To defile; to soil.
• n. - Failure of success when on the point of attainment; defeat; frustration; miscarriage.
• n. - A blunt weapon used in fencing, resembling a smallsword in the main, but usually lighter and having a button at the point.
• n. - The track or trail of an animal.
• n. - A leaf or very thin sheet of metal; as, brass foil; tin foil; gold foil.
• n. - 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.
• n. - Anything that serves by contrast of color or quality to adorn or set off another thing to advantage.
• n. - A thin coat of tin, with quicksilver, laid on the back of a looking-glass, to cause reflection.
• n. - 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.