1. (verb)housebreaking, break-in, breaking and entering trespassing for an unlawful purpose; illegal entrance into premises with criminalintent
2. (verb)break in, break enter someone's (virtual or real) property in an unauthorized manner, usually with the intent to steal or commit a violent act "Someone broke in while I was on vacation"; "They broke into my car and stole my radio!"; "who broke into my account last night?"
3. (verb)chime in, cut in, put in, butt in, chisel in, barge in, break in break into a conversation "her husband always chimes in, even when he is not involved in the conversation"
4. (verb)break in start in a certain activity, enterprise, or role
5. (verb)break in intrude on uninvited "The nosy couple broke in on our conversation"
6. (verb)break in break so as to fall inward "He broke in the door"
7. (verb)break in, break make submissive, obedient, or useful "The horse was tough to break"; "I broke in the new intern"
Definitions of break-in 
