in fencing, a kind of blunt sword, which is tipped with a button covered with leather.

Foil, among jewellers, a thin leaf of metal placed under transparent stones in order to improve their colour or heighten their lustre. Foil also denotes the sheet of tin amalgam laid on the back of a mirror to make it reflect a perfect image. Coloured foils are prepared by covering thin sheets of copper, highly polished, with coloured varnishes.