nageoire

Etymology
From.

Noun

 * 1) fin (of fish)
 * 2) flipper (of dolphin, seal, walrus etc.)

Usage notes
The word nageoire is used to describe non solid fins such as the flipper of a dolphin or the side fins of a tuna. Whereas solid fins placed on the back of any animals such as the ones of a shark or a dolphin, be it mammal or a fish are called ailerons. For non solid back fins (tuna), the term nageoires dorsales is respectively used.