a flat body part like an arm without fingers that some sea animals such as seals and turtles use for swimming （海豹、海龟等的）鳍肢，鳍足 
a long flat piece of rubber or plastic that you wear on your foot to help you swim more quickly, especially below the surface of the water （潜水、游泳用的）脚蹼，蛙鞋，鸭脚板，橡皮脚掌 
a pair of flippers 一双脚蹼
