Noun
1. a piece of thin and flexible sheet metal;
"the photographic film was wrapped in foil"2. anything that serves by contrast to call attention to another thing's good qualities;
"pretty girls like plain friends as foils"3. 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"4. picture consisting of a positive photograph or drawing on a transparent base; viewed with a projector
5. a light slender flexible sword tipped by a button