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See also: FOIL


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Etymology 1[edit]

From Middle English foil, foille, from Old French fueille (plant leaf), from Latin folia, the plural of folium, mistaken as a singular feminine. Doublet of folio.


foil (countable and uncountable, plural foils)

  1. A very thin sheet of metal.
  2. (uncountable) Thin aluminium/aluminum (or, formerly, tin) used for wrapping food.
  3. A thin layer of metal put between a jewel and its setting to make it seem more brilliant.
  4. (figuratively) In literature, theatre/theater, etc., a character who helps emphasize the traits of the main character.
  5. (figuratively) Anything that acts by contrast to emphasise the characteristics of something.
    • Sir Philip Sidney
      As she a black silk cap on him began / To set, for foil of his milk-white to serve.
    • Broome
      Hector has a foil to set him off.
  6. (fencing) A very thin sword with a blunted (or foiled) tip
    • Shakespeare
      Blunt as the fencer's foils, which hit, but hurt not.
    • Mitford
      Socrates contended with a foil against Demosthenes with a sword.
  7. A thin, transparent plastic material on which marks are made and projected for the purposes of presentation. See transparency.
  8. (heraldry) A stylized flower or leaf.
  9. Shortened form of hydrofoil.
  10. Shortened form of aerofoil/airfoil.
Derived terms[edit]

Etymology 2[edit]

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


foil (third-person singular simple present foils, present participle foiling, simple past and past participle foiled)

  1. To prevent (something) from being accomplished.
  2. To prevent (someone) from accomplishing something.
    • Dryden
      And by mortal man at length am foiled.
    • Byron
      her long locks that foil the painter's power
    • 2011 December 10, David Ornstein, “Arsenal 1 - 0 Everton”, in BBC Sport[1]:
      First, former Toffee Mikel Arteta sent Walcott racing clear but instead of shooting he squared towards Ramsey, who was foiled by Tony Hibbert.
    • 2017 August 20, “The Observer view on the attacks in Spain”, in The Observer[2]:
      Many jihadist plots have been foiled and the security apparatus is getting better, overall, at pre-empting those who would do us ill. But, they say, the nature of the threat and the terrorists’ increasing use of low-tech, asymmetrical tactics such as hire vehicles and knives, make it all but impossible to stop every assault.
  3. To blunt; to dull; to spoil.
    to foil the scent in hunting
    (Can we find and add a quotation of Addison to this entry?)
  4. (obsolete) To tread underfoot; to trample.
    • Knowles
      King Richard [] caused the ensigns of Leopold to be pulled down and foiled under foot.
    • Spenser
      Whom he did all to pieces breake and foyle, / In filthy durt, and left so in the loathely soyle.


foil (plural foils)

  1. Failure when on the point of attainment; defeat; frustration; miscarriage.
    (Can we find and add a quotation of Milton to this entry?)
    • Dryden
      Nor e'er was fate so near a foil.
  2. One of the incorrect answers presented in a multiple-choice test.

Etymology 3[edit]

From French foulis.


foil (plural foils)

  1. (hunting) The track of an animal.
  • (track of an animal): spoor

Etymology 4[edit]

From mnemonic acronym FOIL (First Outside Inside Last).


foil (third-person singular simple present foils, present participle foiling, simple past and past participle foiled)

  1. (mathematics) To expand a product of two or more algebraic expressions, typically binomials.

Etymology 5[edit]

See file.


foil (third-person singular simple present foils, present participle foiling, simple past and past participle foiled)

  1. (obsolete) To defile; to soil.


Old French[edit]

Alternative forms[edit]


Latin folium. Compare fueille, from the plural of folium, folia.


foil m (oblique plural fouz or foilz, nominative singular fouz or foilz, nominative plural foil)

  1. leaf (green appendage of a plant which photosynthesizes)