WordNet sense 1 (the cardinal number that is the sum of four and one):

five, phoebe, quint, quintet, quintuplet, v, pentad, cinque, fivesome, Little Phoebe

WordNet sense 2 (one of a pair of decorations projecting above the rear fenders of an automobile):

tailfin, tail fin

WordNet sense 3 (one of a set of parallel slats in a door or window to admit air and reject rain):

louver, Louvre

WordNet sense 4 (a shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)):

flipper