a thin vertical part sticking out of the body of especially a fish or an aircraft that helps balance and movement

We could see the fin of a shark as it slowly circled our boat. 我们能看到绕着我们的船缓缓转圈的鲨鱼的鳍。

a fish's dorsal fin 鱼的背鳍

The aircraft has a long tail fin. 这架飞机的尾翼很长。

a hairstyle, usually worn by men, where the hair is combed from the sides towards the centre so that it sticks up like a fin on top of the head