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  • IPA(key): /fɔɪl/
  • (file)
  • Rhymes: -ɔɪl

Etymology 1Edit

From Middle English foil, foille, from Old French fueille (plant leaf), from Late 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. (authorship, figuratively) In literature, theatre/theater, etc., a character who helps emphasize the traits of the main character and who usually acts as an opponent or antagonist.
  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. A hydrofoil.
  10. An aerofoil/airfoil.
Derived termsEdit

Etymology 2Edit

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 3Edit

From French foulis.


foil (plural foils)

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

Etymology 4Edit

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 5Edit

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 FrenchEdit

Alternative formsEdit


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)