a stabilizer on a ship that resembles the fin of a fish
"The new yacht features a sleek, vertical fin at its stern to help stabilize it in rough seas."
organ of locomotion and balance in fishes and some other aquatic animals
"The salmon used its tail fin to propel itself rapidly through the rushing water while maintaining perfect balance."
One of the appendages of a fish, used to propel itself and to manoeuvre/maneuver.
"He paid for his lunch by handing over a fin to the waitress."
a five-pound (£5) note; the sum of five pounds.
In plain English: A fin is a flat, blade-like part on an animal's tail that helps it steer and swim through water.
"The chef added butter and lemon juice to melt off the fish's fin before serving it."
Usage: Use "fin" as a noun to describe either an appendage on a fish or colloquially for a British £5 banknote. When referring specifically to removing these body parts, use the verb form rather than treating it solely as a physical object.
equip (a car) with fins
"The mechanic decided to fin the rear of the hot rod to improve its aerodynamics."
propel oneself through the water in a finning motion
"The swimmer propelled herself through the calm lake by kicking her legs in a rapid finning motion."
show the fins above the water while swimming
"The sharks were finning near the surface"
To cut the fins from a fish, shark, etc.
"The chef carefully finned the shark before preparing it for the market."
In plain English: To fin means to punish someone by making them do extra work as part of their job duty.
"The chef decided to fin off any burnt edges from the toast before serving it."
commune in the Somme department in France
"Residents of Fin, a small commune in the Somme department in France, gathered to celebrate their local festival."
The word "fin" comes from the Germanic root finno, which originally meant a fish's dorsal fin. It traveled into English through Middle and Old English while retaining this specific meaning of a swimming aid on an animal or boat.