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1. Organ of locomotion and balance in fishes and some other aquatic animals
    
2. One of a pair of decorations projecting above the rear fenders of an automobile
   - tail fin, tailfin
    
3. One of a set of parallel slats in a door or window to admit air and reject rain
   - louver [US], louvre
    
4. A shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)
   - flipper
    
5. A stabilizer on a ship that resembles the fin of a fish
    
6. [US, informal] A United States bill worth 5 dollars
   - fiver [US, informal], five-spot [US], five dollar bill [US]

1. Equip (a car) with fins
    
2. (water sport) propel oneself through the water in a finning motion
    
3. Show the fins above the water while swimming
   "The sharks were finning near the surface";
   - break water

Sounds like: filters, philtres, philt, fin

Derived forms: fins, finning, finned

Type of: appendage, bank bill, bank note, banker's bill [N. Amer], banknote, bill [N. Amer], decoration, equip, extremity, Federal Reserve note [US], fit, fit out, government note [US], greenback [US, informal], member, note, ornament, ornamentation, outfit, shoe, slat, spline, stabiliser [Brit], stabilizer, swim

Part of: auto [informal], autocar [archaic], automobile [N. Amer], car, fish, jalousie, motorcar, ship, wheel [informal], whip [US, informal]

Encyclopedia: Fin, Iran