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Definition of fin

fin

/fɪn/
fin

Plural:fins
•
Adjective:finned
•
Past Simple:finned
•
Past Participle:finned
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Present Participle:finning
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fin Lexical Profile

fin Game Scores & Validity

• noun

1

A flattened appendage on various marine and aquatic animals, such as fish and cetaceans, used for propulsion, steering, and balancing in the water.

Example

"The shark's dorsal fin sliced ominously through the surface of the water."


2

A fixed or movable aerodynamic or hydrodynamic surface on a vehicle, such as an aircraft, rocket, or surfboard, designed to provide stability or control.

Example

"The rocket was designed with four carbon-fiber fins at its base to ensure a stable flight path."


3

American A five-dollar bill.

Example

"He handed the cashier a fin and told her to keep the change."

Synonyms
View all synonyms for fin

• verb

1

To move through the water by moving one's fins or using flippers.

Example

"The scuba diver finned gracefully over the colorful coral reef."


2

To cut the fins from a fish, particularly in the controversial practice of removing a shark's fins and discarding the body.

Example

"The poachers were caught illegally finning sharks in the marine sanctuary."


3

To equip an object, such as a heat sink or an aerodynamic vehicle, with fins.

Example

"The manufacturer finned the engine block to drastically improve heat dissipation during operation."

• Rhymes for fin

Word Origin & Etymology

From Middle English 'finne', from Old English 'finn', tracing back to Proto-Germanic '*finnō' (meaning 'fin'). The American slang sense for a five-dollar bill derives from the Yiddish word 'finf' (five).

Usage Trend

Historical frequency of usage in published text.

180019102020

Cite this Entry


Wordmom. (2026). Definition of Fin. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/fin
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