foil

1 of 5

verb (1)

ˈfȯi(-ə)l 

foiled; foiling; foils

transitive verb

1

a

: to prevent from attaining an end : defeat

They are always able to foil their enemies.

Her accident foiled her from becoming a dancer.

b

: to bring to naught : thwart

foiled the plot

Police foiled an attempted robbery.

2

obsolete : trample

foil

2 of 5

noun (1)

1

: very thin sheet metal

aluminum foil

2

: a thin piece of material (such as metal) put under an inferior or paste stone to add color or brilliance

3

: someone or something that serves as a contrast to another

acted as a foil for a comedian

4

a

: an indentation between cusps in Gothic tracery

b

: one of several arcs that enclose a complex figure

5

: hydrofoil sense 1

foil

3 of 5

verb (2)

foiled; foiling; foils

transitive verb

1

: to back or cover with foil

2

: to enhance by contrast

foil

4 of 5

noun (2)

1

: a light fencing sword having a usually circular guard and a flexible blade of rectangular section tapering to a blunted point compare épée, saber

2

: the art or sport of fencing with the foil

—often used in plural

foil

5 of 5

noun (3)

1

archaic : defeat

2

archaic : the track or trail of an animal

Synonyms of foil

Verb (1)

• frustrate
• thwart
• baffle
• hamper
• prevent
• defeat

Choose the Right Synonym for foil

frustrate, thwart, foil, baffle, balk mean to check or defeat another's plan or block achievement of a goal.

frustrate implies making vain or ineffectual all efforts however vigorous or persistent.

frustrated attempts at government reform

thwart suggests frustration or checking by crossing or opposing.

the army thwarted his attempt at a coup

foil implies checking or defeating so as to discourage further effort.

foiled by her parents, he stopped trying to see her

baffle implies frustration by confusing or puzzling.

baffled by the maze of rules and regulations

balk suggests the interposing of obstacles or hindrances.

officials felt that legal restrictions had balked their efforts to control crime

Examples of foil in a Sentence

Verb (1)

in popular fiction the hero will always foil the villain's plans

Recent Examples on the Web

Verb

The three remaining liberal Justices need only two conservatives to join their side in order to foil the Administration’s plan. —Ruth Marcus, New Yorker, 1 Apr. 2026

Things got worse for the Wild a few shifts later when Spurgeon foiled a Florida rush to the Minnesota net, but went down at full speed and slid hard into the goalpost, knocking the net off the moorings. —Jess Myers, Twin Cities, 27 Mar. 2026

Noun

Yahoo will be competing against a familiar foil in Google, which remains the same formidable force that spelled the company’s demise 20 years ago and has been progressively layering more AI into its search engine with its Gemini technology. —Michael Liedtke, Fortune, 29 Mar. 2026

Design grows dense forests of carbon nanotubes The design grows dense forests of carbon nanotubes directly onto copper foil and coats them with a thin layer of silicon, creating a flexible, conductive scaffold that can absorb expansion while maintaining performance. —Prabhat Ranjan Mishra, Interesting Engineering, 28 Mar. 2026

Word History

Etymology

Verb (1)

Middle English foilen "to trample, tread upon, mortify (the flesh), oppress," alteration of fullen "to full (cloth), trample down, oppress," perhaps by analogy with loanwords from French with palatal l that result in variants with -oi- and -u-, as coilen, cullen "to select for quality, pick out, cull entry 1" — more at full entry 5

Noun (1)

Middle English, leaf, from Anglo-French fuille, foille (from Latin folia, plural of folium) & fuil, from Latin folium — more at blade

Noun (2)

origin unknown

Noun (3)

derivative of foil entry 1

First Known Use

Verb (1)

14th century, in the meaning defined at sense 2

Noun (1)

14th century, in the meaning defined at sense 1

Verb (2)

1611, in the meaning defined at sense 1

Noun (2)

1594, in the meaning defined at sense 1

Noun (3)

15th century, in the meaning defined at sense 1

Phrases Containing foil

• aluminum foil
• silver foil

Rhymes for foil

• boil
• broil
• coil
• oil
• roil
• soil
• spoil
• toil
• voile
• aerofoil
• cinquefoil
• hydrofoil

Kids Definition

foil

1 of 3 verb

ˈfȯi(ə)l 

: to prevent from achieving a goal : defeat

foil a plot

foil

2 of 3 noun

1

: a very thin sheet of metal

tin or aluminum foil

2

: one that serves as a contrast to another

acted as a foil for the comedian

foil

3 of 3 noun

: a fencing weapon having a light flexible blade with a blunt point

Etymology

Verb

Middle English foilen "to trample underfoot," from early French fuller, fouler "to shrink and thicken (cloth), trample underfoot," from Latin fullare "to shrink and thicken (cloth)"

Noun

Middle English foil "leaf," from early French fuille, foille (same meaning), derived from Latin folium "leaf" — related to foliage

Noun

origin unknown

Medical Definition

foil

noun

ˈfȯil 

: very thin sheet metal (as of gold or platinum) used especially in filling teeth