break-in (Noun) — Trespassing for an unlawful purpose; illegal entrance into premises with criminal intent.
break-in (Verb) — Enter someone's (virtual or real) property in an unauthorized manner, usually with the intent to steal or commit a violent act. ex. "Someone broke in while I was on vacation"
break-in (Verb) — Break into a conversation. ex. "her husband always breaks in, even when he is not involved in the conversation"
break-in (Verb) — Start in a certain activity, enterprise, or role.
break-in (Verb) — Intrude on uninvited. ex. "The nosy couple broke in on our conversation"
break-in (Verb) — Break so as to fall inward. ex. "He broke in the door"
break-in (Verb) — Make submissive, obedient, or useful. ex. "I broke in the new intern"