Meaning

• A very thin sheet of metal.

• Thin aluminium/aluminum (or, formerly, tin) used for wrapping food.

  "wrap the sandwich up in foil"

• A thin layer of metal put between a jewel and its setting to make it seem more brilliant.

• (authorship) In literature, theatre/theater, etc., a character who helps emphasize the traits of the main character and who usually acts as an opponent or antagonist.

• Anything that acts by contrast to emphasise the characteristics of something.

• A very thin sword with a blunted (or foiled) tip

• A thin, transparent plastic material on which marks are made and projected for the purposes of presentation. See transparency.

• A stylized flower or leaf.

• A hydrofoil.

• An aerofoil/airfoil.

Meaning

• To cover or wrap with foil.