12. (n.)foil a flexible four-sided rapier having a blunt point.
13. foil foils, the art or practice of fencing with this weapon, points being made by touching the trunk of the opponent's body with the tip of the weapon.
Etymology: (1585–95; orig. uncert.)
Definition of 'Foil'
Princeton's WordNet
1. (noun)foil a piece of thin and flexible sheet metal "the photographic film was wrapped in foil"
2. (noun)foil, enhancer anything that serves by contrast to call attention to another thing's good qualities "pretty girls like plain friends as foils"
3. (noun)hydrofoil, foil a device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through "the fins of a fish act as hydrofoils"
4. (noun)foil, transparency picture consisting of a positive photograph or drawing on a transparent base; viewed with a projector
5. (verb)foil a light slender flexible sword tipped by a button
6. (verb)foil enhance by contrast "In this picture, the figures are foiled against the background"
7. (verb)thwart, queer, spoil, scotch, foil, cross, frustrate, baffle, bilk hinder or prevent (the efforts, plans, or desires) of "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"
8. (verb)foil cover or back with foil "foil mirrors"
5. (noun)Foil a thin leaf of sheetcopper silvered and burnished, and afterwards coated with transparent colors mixed with isinglass; -- employed by jewelers to givecolor or brilliancy to pastes and inferior stones
7. (noun)Foil a thin coat of tin, with quicksilver, laid on the back of a looking-glass, to causereflection
8. (noun)Foil 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