Dic: compulsion

─ WordNet:

1. an urge to do or say something that might be better left undone or unsaid; irresistible impulse
2. an irrational motive for performing trivial or repetitive actions against your will; obsession
3. using force to cause something; coercion

─ Cobuild/LDOCE

1 [N-COUNT] oft N to-inf | A compulsion is a strong desire to do something, which you find difficult to control. (= urge)
cf. a strong and unreasonable desire to do something (→ compel)

• He felt a sudden compulsion to drop the bucket and run...
• The desire to laugh became a compulsion. 　
• Leith felt an overwhelming compulsion to tell him the truth.　
• the compulsion to smoke or eat too much

2 [N-UNCOUNT] If someone uses compulsion in order to get you to do something, they force you to do it, for example by threatening to punish you if you do not do it. (= coercion)

• Many universities argued that students learned more when they were in classes out of choice rather than compulsion...