E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Foil.
That which sets off something to advantage. The allusion is to the metallic leaf used by jewellers to set off precious stones. (French, feuille; Latin, folium; Greek, phullon, a leaf.)
1
“Hector, as a foil to set him off.”
Broome.
“I’ll be your foil, Laertes. In mine ignorance
Your skill shall, like a star i’ the darkest night,
Stick flery off indeed.”
Shakespeare: Hamlet, v. 2.
He foiled me. He outwitted me.
2
“If I be foiled, there is but one ashamod who never was gracious.”—Shakespeare: As You Like It, i. 2.
To run a foil. To puzzle; to lead astray. The track of game is called its foil; and an animal hunted will sometimes run back over the same foil in order to mislead its pursuers.
