fin

fin (http://definr.com/fin)

     n 1: the cardinal number that is the sum of four and one [syn: five,
           5, V, cinque, quint, quintet, fivesome, quintuplet,
           pentad, Phoebe, Little Phoebe]
     2: one of a pair of decorations projecting above the rear
        fenders of an automobile [syn: tail fin, tailfin]
     3: one of a set of parallel slats in a door or window to admit
        air and reject rain [syn: louver, louvre]
     4: a shoe for swimming; the paddle-like front is an aid in
        swimming (especially underwater) [syn: flipper, flippers,
         fins]
     5: a stabilizer that resembles the fins of a fish
     6: organ of locomotion and balance in fishes and some other
        aquatic animals
     v 1: equip with fins, as of a car
     2: propel oneself through the water in a finning motion
     3: show the fins above the water while swimming (of fish); "The
        sharks were finning near the surface" [syn: break water]