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

4 of 4

abbreviation

1

finance; financial

2

finish

Examples of fin in a Sentence

Recent Examples on the Web

Noun

Engineers were still assessing the cause, which may have been an issue with the rocket’s stabilizing fins. —Eric Berger, ArsTechnica, 12 June 2026

Modern ships are also equipped with stabilizers, or retractable fins located below the waterline that help reduce side-to-side rolling. —Linnea Bailey, Southern Living, 9 June 2026

Verb

This plan included a prohibition on shark finning -- the process of removing shark fins at sea and discarding the rest of the shark -- and grouping sharks into different complexes to simplify the management of dozens of species. —Julia Jacobo, ABC News, 1 June 2026

Shark finning is the practice of removing a shark’s fins and dumping the rest of the body at sea, the National Oceanic and Atmospheric Administration said. —Don Sweeney april 29, Sacbee.com, 29 Apr. 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