a very strong feeling of wanting to do something repeatedly that is difficult to control

For many people, dieting is a compulsion. 许多人都有节食的冲动。

[ + to infinitive ] I seem to have a constant compulsion to eat. 我好像总有想吃东西的欲望。

a force that makes you do something

He seems to be driven by some kind of inner compulsion. 他似乎受到某种内在力量的驱使。

[ + to infinitive ] We were under no compulsion to attend. 我们并不是非要去参加不可。

Don't feel under any compulsion to take me with you. 你不必非要勉强带我跟你一起去。