1 of 4

noun (1)

: an external membranous process of an aquatic animal (such as a fish) used in propelling or guiding the body see fish illustration
: something resembling a fin: such as
: hand, arm
: an appendage of a boat (such as a submarine)
: an airfoil attached to an airplane for directional stability
: any of the projecting ribs on a radiator or an engine cylinder
finlike adjective


2 of 4


finned; finning

transitive verb

: to equip with fins

intransitive verb

: to show the fins above the water
: to move through water propelled by fins


3 of 4

noun (2)

: a 5-dollar bill


4 of 4


finance; financial

Examples of fin in a Sentence

Recent Examples on the Web
There were fins to the left, fins to the right and fins on the stage — Crow couldn’t resist joining in. Mikael Wood, Los Angeles Times, 12 Apr. 2024 There were fins on stage, fins to the left and fins to the right. Bryan Alexander, USA TODAY, 12 Apr. 2024 These rules were intended to decrease the animals’ suffering from finning and prevent them from being killed just for their fins. Catherine Duncan, Smithsonian Magazine, 16 Jan. 2024 Conservationists have long railed against the practice of finning sharks, and there are more bans in place now than ever. Justin Klawans, theweek, 31 Jan. 2024 But regulations that directly target shark mortality—not finning alone—should be pursued to protect sharks as a whole, the study authors tell Live Science’s Melissa Hobson. Catherine Duncan, Smithsonian Magazine, 16 Jan. 2024 By the 1920s, humpbacks were scarce, so the industry began targeting blue whales and then fin and sei whales. Douglas Main, Smithsonian Magazine, 18 Jan. 2024 Three decades into his projet sans fin, Invader is more monomaniacal than ever. Lauren Collins, The New Yorker, 11 Dec. 2023 The Falcon 9 first stage tucks its grid fins down during launch, minimizing atmospheric drag on the way up through Earth's atmosphere. Eric Berger, Ars Technica, 17 Nov. 2023
The album cover features Lipa with her hair dyed red for this new era of music, chilling in the ocean with a shark fin, which could signal trouble, prominently poking out of the water. Mariyam Muhammad, The Enquirer, 3 May 2024 The corpses are washing up by the thousands on Southern California’s beaches: a transparent ringed oval like a giant thumbprint 2 to 3 inches long, with a sail-like fin running diagonally down the length of the body. Corinne Purtill, Los Angeles Times, 3 May 2024 Risso’s dolphins, also called gray dolphins, are known for their distinct features – their tall, sharp fin and battle scars from fighting with other dolphins. Julia Daye, Sacramento Bee, 23 Apr. 2024 Creased metal adorned the back end of sedans like the Chevrolet Bel Air in the form of stylish fins, and trunks were massive. Kristin Shaw, Popular Science, 17 Apr. 2024 Their fins have white edges that vary in thickness, the study said. Aspen Pflughoeft, Miami Herald, 2 Apr. 2024 In one scene, Godzilla heads to the Arctic Ocean and threatens a sea serpent with bioluminescent fins that emit a neon-pink glow (hell yeah!). Shirley Li, The Atlantic, 29 Mar. 2024 With its intensive gear, such as heavy oxygen tanks and fins, and the challenges of navigating the underwater world, most people wouldn’t think of scuba diving as an easily adaptive sport. Kathleen Wong, USA TODAY, 14 Apr. 2024 First, there’s a realistic-looking shark with an open mouth, pointy teeth, reflective eyes, and moveable fins. Alida Nugent, Peoplemag, 10 Apr. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'fin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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


1933, in the meaning defined at transitive sense

Noun (2)

1916, in the meaning defined above

Time Traveler
The first known use of fin was before the 12th century

Dictionary Entries Near fin

Cite this Entry

“Fin.” Dictionary, Merriam-Webster, Accessed 20 May. 2024.

Kids Definition


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

More from Merriam-Webster on fin

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!