tailfin

tail fin also tail·fin (tlfn)

n.

1. A fin at the posterior part of the body of a fish, crustacean, whale, or other aquatic animal.

2. An ornamental projection shaped like a fin on the rear fender of an automobile. Also called fin¹.

Thesaurus

Noun	1.	tailfin - a stabilizer that is part of the vertical tail structure of an airplane tail fin, vertical fin, vertical stabiliser, vertical stabilizer stabilizer - airfoil consisting of a device for stabilizing an aircraft vertical tail - the vertical airfoil in the tail assembly of an aircraft
	2.	tailfin - one of a pair of decorations projecting above the rear fenders of an automobile fin, tail fin auto, automobile, car, motorcar, machine - a motor vehicle with four wheels; usually propelled by an internal combustion engine; "he needs a car to get to work" decoration, ornament, ornamentation - something used to beautify