foil

Concise Oxford English Dictionary © 2008 Oxford University Press:
foil1

▶verb

• 1 prevent the success of.

• 2 Hunting (of a hunted animal) cross (a scent or track) in such a way as to confuse the hounds.

▶noun

• 1 Hunting the track or scent of a hunted animal.

• 2 archaic a setback or defeat.

– origin ME (in the sense ‘trample down’): perh. from OFr. fouler ‘to full cloth, trample’, based on L. fullo ‘fuller’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
foil2

▶noun

• 1 metal hammered or rolled into a thin flexible sheet.

  ■ a thin leaf of metal placed under a precious stone to increase its brilliance.

• 2 a person or thing that contrasts with and so enhances the qualities of another.

• 3 Architecture a leaf-shaped curve formed by the cusping of an arch or circle.

– origin ME: via OFr. from L. folium ‘leaf’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
foil3

▶noun a light, blunt-edged fencing sword with a button on its point.

– derivatives
foilist noun.

– origin C16: of unknown origin.

Concise Oxford English Dictionary © 2008 Oxford University Press:
foil4

▶noun each of the structures fitted to a hydrofoil's hull to lift it clear of the water at speed.