Open English Wordnet
Nouns
(n)foila piece of thin and flexible sheet metal“the photographic film was wrapped in foil” (n)foil, enhanceranything that serves by contrast to call attention to another thing's good qualities“pretty girls like plain friends as foils” (n)hydrofoil, foila device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through“the fins of a fish act as hydrofoils” (n)foil, transparencypicture consisting of a positive photograph or drawing on a transparent base; viewed with a projector (n)foila light slender flexible sword tipped by a button Verbs
(v)foilenhance by contrast“In this picture, the figures are foiled against the background” (v)thwart, queer, spoil, scotch, foil, cross, frustrate, baffle, bilkhinder or prevent (the efforts, plans, or desires) of“What ultimately frustrated every challenger was Ruth's amazing September surge”,
“foil your opponent” (v)foilcover or back with foil“foil mirrors”