Let's practice with the foil.

Be careful about the aluminum foil covering the bottom of the plate, don't burn yourself!

The old man spoke and, with a feeble throw, / at Pyrrhus with a harmless dart he drave. / The jarring metal blunts it, and below / the shield-boss, down it hangs, and foils the purposed blow.

A little old woman foiled the robbery by whacking the thief on the head with her cane.

Let's practice foil fencing.

This threatens to foil our plans.

Regicide is a foil to the divine right of kings.

I was foiled in my attempt.

Investigators foiled a plot to hijack an airplane.

Yanni found a new job at an aluminum foil factory.