fin in WordNet English dictionary

1. the cardinal number that is the sum of four and one
   five  5  V  cinque  quint  quintet  fivesome  quintuplet  pentad  fin  Phoebe  Little Phoebe 
   
2. organ of locomotion and balance in fishes and some other aquatic animals
   fin 
   
3. a stabilizer on a ship that resembles the fin of a fish
   fin 
   
4. one of a set of parallel slats in a door or window to admit air and reject rain
   louver  louvre  fin 
   
5. a shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)
   flipper  fin 
   
6. one of a pair of decorations projecting above the rear fenders of an automobile
   tail fin  tailfin  fin 
   

1. show the fins above the water while swimming
   "The sharks were finning near the surface"
   fin  break water 
   
2. propel oneself through the water in a finning motion
   fin 
   
3. equip (a car) with fins
   fin