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 foiling boat will be built on Navier’s Pioneer hull, which Robb Report has tested over the last three years in multiple forms, including the first production model last week at FLIBS. —Michael Verdon, Robb Report, 3 Nov. 2025

Linking hubs such as Oakland, Richmond, Oyster Point, and Redwood City with high-speed foiling ferries would put hundreds of thousands more workers within a 45-minute commute of San Francisco’s job centers, expanding housing supply and cutting emissions from car commutes across the Bay. —Big Think, 28 Oct. 2025

Noun

To manage cold temperatures, an internal heating structure composed of a thin film of nickel foil (approximately 10 microns thick) will be added to the battery. —Mrigakshi Dixit, Interesting Engineering, 5 Nov. 2025

That sensibility is countered by Dina’s, who plays the romantic foil to Liberty’s pessimist. —Tom Smyth, Vulture, 5 Nov. 2025

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