fin

1 of 4

noun (1)

ˈfin 

1

: an external membranous process of an aquatic animal (such as a fish) used in propelling or guiding the body see fish illustration

2

: something resembling a fin: such as

a

: hand, arm

b(1)

: an appendage of a boat (such as a submarine)

(2)

: an airfoil attached to an airplane for directional stability

c

: flipper sense 1b

d

: any of the projecting ribs on a radiator or an engine cylinder

finlike

ˈfin-ˌlīk 

adjective

fin

2 of 4

verb

finned; finning

transitive verb

: to equip with fins

intransitive verb

1

: to show the fins above the water

2

: to move through water propelled by fins

fin

3 of 4

noun (2)

slang

: a 5-dollar bill

fin

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abbreviation

1

finance; financial

2

finish

Examples of fin in a Sentence

Recent Examples on the Web

Noun

Cruise passengers may also see fin or humpback whales plus Common dolphins. —Holly Andres, Daily News, 26 Mar. 2026

So, biologists tagged Lee’s largemouth, took fin and scale samples for analysis, and gave the live bass back to Lee. —Bob McNally, Outdoor Life, 25 Mar. 2026

Verb

Everything, from the wheel well curve of the race-winning 1963 Ferrari 250 GTO that sold for $70 million at auction in 2018, to the distinctive rear spoiler on a F40, or the distinctive carbon fiber fins on a limited-edition Ferrari Daytona SP3 was simply beautiful. —Bill Springer, Forbes.com, 19 Feb. 2026

In only three years, traders trafficked fins from over 36,000 illegally caught oceanic whitetip sharks. —Juan Carlos Navarro, Time, 2 Feb. 2026

Word History

Etymology

Noun (1)

Middle English finn, from Old English

Noun (2)

Yiddish finf five, from Middle High German, from Old High German — more at five

First Known Use

Noun (1)

before the 12th century, in the meaning defined at sense 1

Verb

1861, in the meaning defined at intransitive sense 2

Noun (2)

1916, in the meaning defined above

Phrases Containing fin

• dorsal fin
• fin de siècle
• fin whale
• lobe-fin
• pectoral fin
• pelvic fin
• swim fin
• tail fin

Rhymes for fin

• been
• bin
• chin
• din
• djinn
• finn
• gin
• grin
• in
• kin
• linn
• linne

Kids Definition

fin

noun

ˈfin

1

: a thin process on the outside of an aquatic animal (as a fish or whale) used in propelling or guiding the body

2

: something shaped like a fin

finlike

-ˌlīk

adjective

finned

ˈfind

adjective