from The American Heritage® Dictionary of the English Language, 4th Edition

  • transitive v. To prevent from being successful; thwart.
  • transitive v. To obscure or confuse (a trail or scent) so as to evade pursuers.
  • n. Archaic A repulse; a setback.
  • n. Archaic The trail or scent of an animal.
  • n. A thin, flexible leaf or sheet of metal: aluminum foil.
  • n. A thin layer of polished metal placed under a displayed gem to lend it brilliance.
  • n. One that by contrast underscores or enhances the distinctive characteristics of another: "I am resolved my husband shall not be a rival, but a foil to me” ( Charlotte Brontë).
  • n. The reflective metal coating on the back of a glass mirror.
  • n. Architecture A curvilinear, often lobelike figure or space formed between the cusps of intersecting arcs, found especially in Gothic tracery and Moorish ornament.
  • n. An airfoil.
  • n. Nautical A hydrofoil.
  • transitive v. To cover or back with foil.
  • transitive v. To set off by contrast.
  • n. A fencing sword having a usually circular guard and a thin, flexible four-sided blade with a button on the tip to prevent injury.
  • n. The art or sport of fencing with such a sword. Often used in the plural: a contest at foils.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A very thin sheet of metal.
  • n. Thin aluminium/aluminum (or, formerly, tin) used for wrapping food.
  • n. A thin layer of metal put between a jewel and its setting to make it seem more brilliant.
  • n. In literature, theatre/theater, etc, a character who helps emphasize the traits of the main character.
  • n. Anything that acts to emphasise the characteristics of something.
  • n. A very thin sword with a blunted (or foiled) tip
  • n. A thin, transparent plastic material on which marks are made and projected for the purposes of presentation. See transparency.
  • n. A stylized flower or leaf.
  • n. Shortened form of hydrofoil.
  • n. Shortened form of aerofoil/airfoil.
  • n. The track of an animal.
  • v. To prevent (something) from being accomplished.
  • v. To prevent (someone) from accomplishing something.
  • v. To multiply two binomials together.

from the GNU version of the Collaborative International Dictionary of English

  • 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
  • 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.
  • transitive v. To tread under foot; to trample.
  • transitive v. To render (an effort or attempt) vain or nugatory; to baffle; to outwit; to balk; to frustrate; to defeat.
  • transitive v. To blunt; to dull; to spoil.
  • transitive v. To defile; to soil.

from The Century Dictionary and Cyclopedia

  • To trample upon; tread under foot.
  • To blunt; dull; deaden: as, to foil the scent in a chase.
  • To frustrate; baffle; mislead; render vain or nugatory, as an effort or attempt; thwart; balk: as, the enemy was foiled in his attempt to pass the river.
  • This your courtesy
  • Synonyms Thwart, Baffle, etc. See frustrate.
  • To defile: same as file, foul.
  • In hunting, of an animal, to retrace its own track for the purpose of baffling the hounds; ‘run the foil.’ See foil, n.
  • n. A leaf, as of a plant.
  • n. A metallic substance formed into very thin sheets by rolling and hammering: as, gold, tin, or lead foil.
  • n. In jewelry, a thin leaf of metal placed under a precious stone to change its color, or to give it more color in case of its being inferior in that respect, or to give it additional luster by the reflection of light from the surface of the metal.
  • n. Leaf-metal placed behind translucent enamel for the same purpose as that used for precious stones. (See def. 3.) In this sense often called paillon (which see). Hence Anything of a different color or of different qualities which serves to adorn or set off another thing to advantage; that which, by comparison or contrast, sets off or shows more conspicuously the superiority of something else.
  • n. An amalgam of tin with quicksilver laid on one side of a sheet of glass to produce a reflecting surface in making a mirror.
  • n. In medieval architecture, a small arc in the tracery of a window, panel, etc., which is said to be trefoiled, quatrefoiled, cinquefoiled, multifoiled, etc., according to the number of arcs which it contains.
  • n. The track or trail of game when pursued.
  • n. Defeat; frustration; failure when on the point of achievement.
  • n. In wrestling, a partial fall; a fall not complete according to the rules.
  • n. A bated or blunted sword used in fencing-practice and friendly contests; now, usually, an implement used in fencing-schools, for small-sword practice only.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • v. enhance by contrast
  • v. hinder or prevent (the efforts, plans, or desires) of
  • n. 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
  • n. anything that serves by contrast to call attention to another thing's good qualities
  • n. a piece of thin and flexible sheet metal
  • n. a light slender flexible sword tipped by a button
  • v. cover or back with foil
  • n. picture consisting of a positive photograph or drawing on a transparent base; viewed with a projector


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English foilen, to trample, defile, variant of filen, to defile; see file3.
Middle English, from Old French foille, from Latin folia, pl. of folium, leaf; see bhel-3 in Indo-European roots.
Origin unknown.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From French feuille ("plant leaf"), from Latin folia, the plural of folium, mistaken as a singular feminine.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Middle English foilen ("spoil a scent trail by crossing it"), from French fouler ("tread on, trample"), ultimately from Latin fullo ("clothes cleaner, fuller").

from Wiktionary, Creative Commons Attribution/Share-Alike License

From French foulis.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From mnemonic acronym FOIL ("First Outside Inside Last").



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  • Defined by the Century Dictionary as "This your courtesy" - way down at the bottom of the list, no. 5 under the 'Other (7)' heading.

    October 26, 2011

  • Especially in a microwave.

    December 5, 2007