Animals that swim in the water sometimes have flippers. Thes are all considered flippers:

• a duck's feet
• a penguin's wings
• a dolphin's tail
• a sea turtle's legs

There's also a tool that humans use for swimming that is called a "flipper". You wear flippers on your feet when you go diving. They look like big duck feet.

Fish don't have "flippers". Instead, you call the body parts that they swim with "fins".