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