fin

plural fins

1. biologyOne of the appendages of a fish, used to propel itself and to manoeuvre/maneuver.

   The fish's fins minimize water flow.

   1 more example

   Then he commenced to talk, really talk. and inside of two flaps of a herring's fin he had me mesmerized, like Eben Holt's boy at the town hall show. He talked about the ills of humanity, and the glories of health and Nature and service and land knows what all.

   1913, Joseph C[rosby] Lincoln, chapter IV, in Mr. Pratt’s Patients, New York, N.Y.; London: D[aniel] Appleton and Company, →OCLC

2. A similar appendage of a cetacean or other marine animal.

   a dolphin's fin

   Synonyms: flipper

3. A thin, rigid component of an aircraft, extending from the fuselage and used to stabilise and steer the aircraft.

   The fin stabilises the plane in flight.

4. A similar structure protruding from a projectile, used to help keep it on course.
5. hobbiesA similar structure on the bottom of a surfboard, used to help steer it.
6. A hairstyle, resembling the fin of a fish, in which the hair is combed and set into a vertical ridge along the top of the head from about the crown to the forehead.
7. A device worn by divers and swimmers on their feet.

   The divers wore fins to swim faster.

   Synonyms: flipper

8. An extending part on a surface of a radiator, engine, heatsink, etc., used to facilitate cooling.
9. A sharp raised edge (generally in concrete) capable of damaging a roof membrane or vapor retarder.
10. nauticalThe conning tower of a submarine.
11. UKobsoleteslangA person's hand.

    "Done say I to that, Reuben, tip me your fin, my spark, and it shall be a bet."

    1839, Dearden's Miscellany, volumes 1-2, page 661

present singular third person fins · participle present finning · participle past finned · past finned

1. transitiveTo cut the fins from a fish, shark, etc.
2. intransitive(Of a fish) to swim with the dorsal fin above the surface of the water.

   When you spot him finning just under the surface, you move up quietly and present [...] bait, usually a squid.

   1983, The Fisherman Who Laughed, page 54

3. intransitiveTo swim in the manner of a fish.

   A neutrally buoyant diver does not need to fin to maintain depth.

4. transitiveTo provide (a motor vehicle etc) with fins.

plural fins

1. UKslangformerly Australiaa five-pound (£5) note; the sum of five pounds.

   Synonyms: finny, fiver, finnuf

2. USdatedslangA five-dollar bill; the sum of five dollars.

   Synonyms: fiver, Lincoln

plural fins

1. archaicbroadcasting"The end".

   Synonyms: finis

2. obsoleteroad signsDenotes the end of the road.

1. informaluncountablefinasteride

1. commune in the Somme department in France

plural FINs

1. USabbreviationinitialismcommunicationsInitialism of facility ID number.
2. UKabbreviationinitialismgovernmentInitialism of force identification number.
3. abbreviationinitialismInitialism of feminine in nature