tail fin vs ornament

tail fin and ornament both are nouns.

Word	Noun	Adjective	Verb	Adverb
tail fin	Yes	No	No	No
ornament	Yes	No	Yes	No

As nouns, ornament is a hypernym of tail fin; that is, ornament is a word with a broader meaning than tail fin:

tail fin: one of a pair of decorations projecting above the rear fenders of an automobile
ornament: something used to beautify

Other hypernyms of tail fin include decoration, ornamentation.

tail fin (noun)	ornament (noun)
the tail of fishes and some other aquatic vertebrates	something used to beautify
a stabilizer that is part of the vertical tail structure of an airplane
one of a pair of decorations projecting above the rear fenders of an automobile

tail fin (verb)	ornament (verb)
	make more attractive by adding ornament, colour, etc.
	be an ornament to