fin

[ fin ]

/ fɪn /

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noun

a membranous, winglike or paddlelike organ attached to any of various parts of the body of fishes and certain other aquatic animals, used for propulsion, steering, or balancing.

Nautical.

a horizontal, often adjustable, winglike appendage to the underwater portion of a hull, as one for controlling the dive of a submarine or for damping the roll of a surface vessel.
fin keel.

Also called vertical stabilizer .Aeronautics. any of certain small, subsidiary structures on an aircraft, designed to increase directional stability.

any of a number of standing ridges on an ordinarily hot object, as a radiator, a cylinder of an internal-combustion engine, etc., intended to maximize heat transfer to the surrounding air by exposing a large surface area.

any part, as of a mechanism, resembling a fin.

Metallurgy. a ridge of metal squeezed through the opening between two rolls, dies, or halves of a mold in which a piece is being formed under pressure.Compare flash (def. 11).

Automotive. an ornamental structure resembling an aeronautical fin that is attached to the body of an automobile, as on each rear fender (tail fin ).

Slang. the arm or hand.

Usually fins. flipper (def. 2).

verb (used with object), finned, fin·ning.

to cut off the fins from (a fish); carve or cut up, as a chub.

to provide or equip with a fin or fins.

verb (used without object), finned, fin·ning.

to move the fins; lash the water with the fins, as a whale when dying.

QUIZ

THINGAMABOB OR THINGUMMY: CAN YOU DISTINGUISH BETWEEN THE US AND UK TERMS IN THIS QUIZ?

Do you know the difference between everyday US and UK terminology? Test yourself with this quiz on words that differ across the Atlantic.

Question 1 of 7

In the UK, COTTON CANDY is more commonly known as…

candystring

candyfloss

candypuff

TAKE THE QUIZ TO FIND OUT

Origin of fin

First recorded before 1000; Middle English, Old English finn; cognate with Dutch vin, Low German finne; akin to Swedish fena; probably akin to Latin pinna; see also pen¹

OTHER WORDS FROM fin

finless, adjectivefinlike, adjective

Other definitions for fin (2 of 4)

fin²

[ fin ]

/ fɪn /

noun

Slang. a five-dollar bill.

Origin of fin

First recorded in 1865–70; earlier finnip, finnup, fin(n)if “a five-pound note,” from Yiddish fin(e)f “five,” from Middle High German vumf, vimf; see origin at five

Other definitions for fin (3 of 4)

fin.

abbreviation

finance.

financial.

finish.

Other definitions for fin (4 of 4)

Fin.

abbreviation

Finland.

Finnish.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use fin in a sentence

The fins of round gobies can detect textures with a sensitivity similar to that of the pads on monkeys’ fingers, researchers report November 3 in the Journal of Experimental Biology.
A fish’s fins may be as sensitive to touch as fingertips|Carolyn Wilke|November 3, 2020|Science News
Studying fish fins could also lead to new designs for robots that swim and sense underwater and that can explore areas that would otherwise be difficult for people to reach.
A fish’s fins may be as sensitive to touch as fingertips|Carolyn Wilke|November 3, 2020|Science News
The trail culminates with Marys Rock, a 3,514-foot mountain with large granite fins jutting out from the peak that offers long-range views of Shenandoah Valley.
The Ultimate Shenandoah National Park Travel Guide|Graham Averill|October 7, 2020|Outside Online
Today, blue whales and other endangered species, like fin and humpbacks, are recovering, but slowly.
Whale ‘roadkill’ is on the rise off California. A new detection system could help.|Erik Olsen|September 29, 2020|Popular-Science

Because the fin and the binoculars clipped to it stretch the shock cord as they hang, this arrangement supports the weight of the optics while still allowing total freedom of movement.
Get More from Your Binoculars with This $100 Stick|Wes Siler|September 19, 2020|Outside Online

British Dictionary definitions for fin (1 of 5)

fin¹

/ (fɪn) /

noun

any of the firm appendages that are the organs of locomotion and balance in fishes and some other aquatic animals. Most fishes have paired and unpaired fins, the former corresponding to the limbs of higher vertebrates

a part or appendage that resembles a fin

British a vertical surface to which the rudder is attached, usually placed at the rear of an aeroplane to give stability about the vertical axisUS name: vertical stabilizer
a tail surface fixed to a rocket or missile to give stability

nautical a fixed or adjustable blade projecting under water from the hull of a vessel to give it stability or control

a projecting rib to dissipate heat from the surface of an engine cylinder, motor casing, or radiator

(often plural) another name for flipper (def. 2)

verb fins, finning or finned

(tr) to provide with fins

(tr) to remove the fins from (a dead fish)

(intr) (esp of a whale) to agitate the fins violently in the water

Derived forms of fin

finless, adjective

Word Origin for fin

Old English finn; related to Middle Dutch vinne, Old Swedish fina, Latin pinna wing

British Dictionary definitions for fin (2 of 5)

fin²

/ (fɪn) /

noun

US slang a five-dollar bill

Word Origin for fin

from Yiddish finf five, ultimately from Old High German funf, finf

British Dictionary definitions for fin (3 of 5)

Fin

abbreviation for

Finland

Finnish

British Dictionary definitions for fin (4 of 5)

FIN

abbreviation for

Finland (international car registration)

British Dictionary definitions for fin (5 of 5)

fin.

abbreviation for

finance

financial

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for fin

fin

[ fĭn ]

One of the winglike or paddlelike parts of a fish, dolphin, or whale that are used for propelling, steering, and balancing in water.

fin

Origin of fin

OTHER WORDS FROM fin

Other definitions for fin (2 of 4)

Origin of fin

Other definitions for fin (3 of 4)

Other definitions for fin (4 of 4)

Words related to fin

How to use fin in a sentence

British Dictionary definitions for fin (1 of 5)

Derived forms of fin

Word Origin for fin

British Dictionary definitions for fin (2 of 5)

Word Origin for fin

British Dictionary definitions for fin (3 of 5)

British Dictionary definitions for fin (4 of 5)

British Dictionary definitions for fin (5 of 5)

Scientific definitions for fin