How do you say foil in French?

For cooking foil:

* Papier d'aluminium (aluminum paper) is the most common and accurate term.

* Papier alu (aluminum paper) is a shorter, more informal version.

For fencing foil:

* Fleuret is the word for a fencing foil.

For other meanings of "foil" (e.g., as a contrast):

* You would need to translate the specific meaning, as there's no single word for "foil" in this sense. For example:

* Contraste (contrast)

* Opposé (opposite)

* Déjouer (to foil, to thwart)

So, you need to be specific about what kind of "foil" you're referring to in order to get the right French word!