Definitions for "Tail Fin"
a vertical aerodynamic surface, part of the boat's superstructure near the transom, which aids directional stability; typical current designs employ two tail fins or uprights side by side, perhaps 4 to 6 feet apart and slightly splayed; also "air rudder."
the vertical part of an aircraft's tailplane
At the stern of the boat to stop it from bouncing from side to side.
one of a pair of decorations projecting above the rear fenders of an automobile
Keywords:  vertebrates, aquatic, fishes
the tail of fishes and some other aquatic vertebrates