tail fin

(noun) a stabilizer that is part of the vertical tail structure of an airplane. Synonyms: vertical stabilizer, vertical stabiliser, vertical fin, tail fin, tailfin.

(noun) one of a pair of decorations projecting above the rear fenders of an automobile. Synonyms: tail fin, tailfin, fin.

(noun) the tail of fishes and some other aquatic vertebrates. Synonyms: tail fin, caudal fin.