join up (2)
Meaning: If you join up, you enter the military in order to train and become a member of one of the armed forces.Synonym: enlist
- join up Johnny wants to join up and fight in Iraq, but his mum doesn't want him to risk his life in a war she doesn't support.
- join up If you join up, you'll have to fight and kill whoever the government tells you to, even if you don't think it's right.
People who join up are trained to