kick in

verb kicks in · kicking in · kicked in

1. transitive To kick or strike so as to cause the object struck to collapse or fall inwards. Upon hearing residents in the burning house, the passerby kicked in the front door and yelled to those inside.
2. slang, transitive To kick or strike (a person); to beat up.
3. idiomatic, intransitive To start, connect, or take effect, especially in a sudden way; to begin functioning. You have to push the switch hard to get the heater to kick in.
4. slang To join or begin. You should kick in on the work.
5. idiomatic, intransitive, transitive To contribute, especially to a collection of money; to hand over. For the year-end party, we're asking each employee to kick in twenty dollars.
6. idiomatic To die; to give up on something. The business is going to kick in most likely.