foil

a piece of thin and flexible sheet metal

the photographic film was wrapped in foil

enhance by contrast

In this picture, the figures are foiled against the background

hinder or prevent (the efforts, plans, or desires) of

What ultimately frustrated every challenger was Ruth's amazing September surge

anything that serves by contrast to call attention to another thing's good qualities

pretty girls like plain friends as foils

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