tail fin in WordNet English dictionary

1. the tail of fishes and some other aquatic vertebrates
   tail fin  caudal fin 
   
2. one of a pair of decorations projecting above the rear fenders of an automobile
   tail fin  tailfin  fin 
   
3. a stabilizer that is part of the vertical tail structure of an airplane
   vertical stabilizer  vertical stabiliser  vertical fin  tail fin  tailfin 
   

tail fin in English Wiktionary