n.

1. （被）强迫，（被）强制[U][+to-v]
   John will take his medicine only by compulsion.

   只有对他用强制手段约翰才会服药。

2. 强制力，强迫力[U]
3. 【心】强迫作用（一种难以抵制的冲动）[C][+to-v]
   She felt a sudden compulsion to hit him.

   她突然感到一种难以抗拒的冲动，想要揍他。

n.

1. the action of compelling or the state of being compelled; constraint.
2. an irresistible urge to behave in a certain way.