A line associated with the 19th century mustache-twirling stage villains thwarted by the hero was “Curses! Foiled again!”
Foil as a verb meaning “to frustrate the efforts of” is popular with headline writers and journalists.
Netanyahu makes final push to foil Swedish plan to divide Jerusalem
No-shows foil Sunrise mayor’s payment plan for code violators
Police foil plan to kill Dawood’s brother
The verb originated as a hunting term meaning “to spoil a trace or scent by running over it,” from Old French fouler, “trample.” It took on its modern meaning of spoiling someone’s plans in the 1660s.
Foil as a noun meaning “a thin sheet of metal,” comes from a French word for “leaf,” modern French feuille. The sense of “metallic food wrap” dates from 1946.
In fiction, a “foil character” is a secondary character used to point up certain traits in a main character. In Hamlet, for example, Laertes acts as a foil to Hamlet. Whereas Hamlet hesitates to avenge his father’s death, Laertes is quick to seek vengeance for the death of his sister. In Macbeth, the loyal, law-abiding Banquo serves as a foil to ambition-crazed Macbeth. Macbeth murders to win the crown. Banquo does nothing and becomes the father of kings. This idea of the word foil as “contrast” comes from the practice of backing a gem with metal foil to make it shine more brightly. Shakespeare used it in this sense in Henry IV, Part I. The future Henry V is a dissolute prince. In a soliloquy he anticipates changing his ways when he becomes king. He thinks that his subjects will appreciate his reign more because they’ll have his rotten youth to compare it with:
My reformation, glittering o’er my fault,
Shall show more goodly and attract more eyes
Than that which hath no foil to set it off.
This use of the noun foil to mean “contrast” is a favorite with political writers:
Republicans make President Obama foil in state races
Crist Uses His Old Party as a New Foil: He has used the Republican-led state legislature as a conservative foil to increase his appeal among centrist and Democratic voters.
Ehrlich welcomes Palin as a foil: Ehrlich’s camp is embracing Palin’s move as an opportunity to emphasize the former governor’s more moderate profile.
Both noun and verb are used playfully here:
Man’s foil theft plan foiled at Home Depot: A man who tried to foil the theft detection devices at Home Depot with aluminum foil learned Saturday that his scheme would not work.
Foil meaning “a light fencing weapon” is of uncertain origin.