foil

noun

1.
a piece of thin and flexible sheet metal
Derived from:
foil foliate
2.
anything that serves by contrast to call attention to another thing's good qualities
Derived from:
foil
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
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