fin

/fɪn/

the cardinal number that is the sum of four and one

中文释义：鳍；五美元纸币

Sharks use their dorsal fin to maintain stability while swimming.

鲨鱼用背鳍在游泳时保持稳定。

He paid for the meal with a fin, leaving a small tip.

他用一张五美元纸币付了餐费，留了一点小费。