Foil

How to spell foil

4 letters · 1 syllable

How to pronounce foil

What does foil mean?

1. nounA very thin, flexible sheet of metal, especially aluminium used in cooking and packaging.
2. verbTo prevent someone from succeeding in a plan or scheme.
3. nounA light, slender sword with a blunted point used in fencing.
4. nounA person or thing that contrasts with and so highlights the qualities of another.

Foil in a sentence

• noun

  She wrapped the leftover roast in foil before refrigerating it.

• verb

  Quick action by staff helped foil the theft.

• noun

  She gripped the foil and saluted her opponent before the bout.

• noun

  The cheerful sidekick serves as a foil to the brooding hero.

• noun

  A sheet of foil kept the baking tray clean during cooking.

• verb

  The locked vault managed to foil the robbers.

Where does foil come from?

Language of origin: French

The metal and contrast senses of 'foil' trace back to the Latin folium, which simply meant 'leaf', the same root that gives us 'foliage' and 'folio'. Old French turned this into 'foil' or 'foille' for a thin leaf-like sheet, and English borrowed it in the 1300s for hammered sheets of metal so thin they resembled leaves. Because jewellers backed a gemstone with bright metal foil to make it sparkle, the word came to mean anything that sets off something else by contrast, which is how it acquired its theatrical and literary sense of a character who highlights another. The verb meaning 'to thwart or defeat', however, comes from a separate line, the Old French 'fouler' meaning 'to trample or tread underfoot', so frustrating someone was originally pictured as trampling their plans. The thin fencing sword called a foil is of uncertain origin but is usually linked to this idea of blunting or treading down a weapon's point. Because all these threads collapsed into one short spelling, the trap for writers is simply the 'oi' vowel rather than the more obvious 'oy'.

How the word is built

• foil (single root; from Latin folium 'leaf', via Old French)