Real Dictionary

foil
uncountable noun: Foil consists of sheets of metal as thin as paper. It is used to wrap food in.

foil in American English 1
the scent or trail of an animal
to keep from being successful; thwart; frustrate
noun: a defeat; check; repulse
transitive verb: to prevent the success of; frustrate; balk

foil in American English 2
a leaflike, rounded space or design between cusps or in windows, etc., as in Gothic architecture
noun: metal in the form of very thin sheets
transitive verb: to cover or back with foil

foil in American English 3
a long, thin fencing sword with a button on the point to prevent injury
noun: a flexible four-sided rapier having a blunt point

foil in British English 1
to baffle or frustrate (a person, attempt, etc)
noun: any scent that obscures the trail left by a hunted animal

foil in British English 2
noun: metal in the form of very thin sheets

foil in British English 3
noun: a light slender flexible sword tipped by a button and usually having a bell-shaped guard