General English


  • In masonry, one of multiple circular or nearly circular holes, set tangent to the inside of a larger arc, that meet each other in pointed cusps aroundthe arc's inner perimeter.
  • A metal formed into thin sheets by rolling.


  • A thin sheet of a metal. It may be defined as no thicker than a given amount, such as 0.15 mm. An example is the aluminum or tantalum foil utilized in electrolytic capacitors.


  • noun a very thin metal or plastic sheet on a backing, which is peeled off and used to block gold or silver letters on a book cover
  • noun clear stable film used as a carrying surface for film assembly
  • noun metallic paper used for decorative packaging


  • a thin metal capsule covering the cork and top of the neck of a wine bottle

Origin & History of “foil”

English has three separate words foil. The oldest, ‘thwart’ (13th c.), originally meant ‘trample’. It probably comes via Anglo-Norman *fuler from vulgar Latin *fullāre, a derivative of Latin fullō ‘person who cleans and bulks out cloth, originally by treading’ (whence English fuller (OE)). Foil ‘metallic paper’ (14th c.) comes via Old French from Latin folium ‘leaf’ (source also of English foliage (15th c.) and folio (16th c.)). It originally meant ‘leaf’ in English too, but that usage died out in the 15th century. The modern notion of ‘one that enhances another by contrast’ comes from the practice of backing a gem with metal foil to increase its brilliancy, (Latin folium, incidentally, goes back to an Indo-European *bhel-, an extended form of which, *bhlō-, produced English blade, bloom, blossom, and flower.) The source of foil ‘sword’ (16th c.) is not known, although the semantic development of blade from ‘leaf’ to ‘cutting part’ suggests the possibility that a similar process took place in the case of foil ‘leaf’.