definition of
foil

[1] #1 foil n. a piece of thin and flexible sheet metal; "the photographic film was wrapped in foil". wn

[2] #2 foil v. enhance by contrast; "In this picture, the figures are foiled against the background". wn

[3] #3 foil v. [thwart, queer, spoil, scotch, cross, frustrate, baffle, bilk] hinder or prevent (the efforts, plans, or desires) of; "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent". wn

[4] #4 foil n. [enhancer] anything that serves by contrast to call attention to another thing's good qualities; "pretty girls like plain friends as foils". wn

[5] #5 foil n. [hydrofoil] a 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". wn