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

The fins were dried, collected and later analyzed by researchers. — Melissa Cristina Márquez, Forbes.com, 1 July 2026

The list of fireworks that aren’t allowed includes bottle rockets, Roman candles, illuminating torches, missiles with fins or rudders and single or multi-shot parachutes with night effects. — Rashad Alexander, Kansas City Star, 30 June 2026

Verb

But instead of being a family affair, this time around Ronald D. Moore and his writing staff amplified the grim joyless aspects of this ragtag fleet of colony ships trying to fin d a shining planet called Earth before the evil Cylons annihilated them. — Jeff Spry, Space.com, 17 June 2026

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

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