What does foil mean?
Foil is a small word with several well-established meanings. As a verb, it means to thwart: to stop a plan, crime, or attack from succeeding, a sense that dominates headlines about plots 'foiled' by police. As a noun, foil most familiarly names the thin, flexible sheet of metal — usually aluminium — used in kitchens for wrapping food and covering dishes. It also denotes the lightest of the three fencing swords, a thrusting weapon scored on the torso, and in literary criticism it describes a character who contrasts with another so that each one's traits stand out more clearly. The word traces back ultimately to the Latin folium, meaning leaf, because early foil was made by hammering metal into leaves thin as foliage. Versatile and frequently encountered, foil moves easily between the kitchen, the sports piste, the news report, and the literature classroom.
To prevent someone or something from succeeding in a plan, enterprise, or criminal act; to thwart.
"Border officials foiled an attempt to smuggle rare orchids across the frontier."
Most often seen in journalism, typically describing police, security, or intelligence action against crime or plots.
Metal hammered or rolled into a very thin, flexible sheet, now almost always aluminium, used chiefly for wrapping and covering food.
"Cover the dish with foil and bake for twenty minutes."
In the UK this is often called 'kitchen foil'; in the US, 'aluminum foil'.
In literature and drama, a character who contrasts with another — usually the protagonist — so as to highlight particular qualities of both.
"Steady, cautious Horatio serves as a foil to impulsive Prince Hamlet."
A light fencing sword with a narrow blade and a small guard, used for thrusting; the target area is the torso.
"She took up the foil at her first fencing lesson."
Used when referring to multiple items or instances, e.g. several sheets of foil, several fencing weapons, or several contrasting characters.
"The museum displays a collection of antique duelling foils."
The same little word covers kitchen wrap, an Olympic sword, Hamlet's mirror, and every villain's ruined scheme.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of foil
The noun foil derives, through Old French, from the Latin folium ('leaf'), since the earliest metal foil was hammered into sheets as thin as leaves; the literary sense of a contrasting character grew out of this idea of setting jewels or figures against foil to show them off. The verb foil, meaning to thwart, entered English in the early modern period and came to describe trampling or defeating an opponent's efforts. Cognates from the same Latin root include foliage, folio, and foliate.
How foil is actually used
The verb is common in news reporting ('police foiled an attack') and carries a neutral-to-positive tone. In literary discussion, 'foil' refers specifically to deliberate contrast between characters — Hamlet and Laertes are the classic example. In British usage 'kitchen foil' is the usual everyday phrase, while American usage favours 'aluminum foil'.