flipper flipper /ˈflɪpɝ/

noun

1. The flat broad limb of aquatic animals specialized for swimming  ( flipper )
   the flat broad limb of aquatic animals specialized for swimming
   
2. A shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)  ( fin , flipper )
   a shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)
    I always wear my trusty flippers when snorkeling to help me swim more efficiently
   I always wear my trusty flippers when snorkeling to help me swim more efficiently