Burst in on Definition 1 of 2Pro Tip 1/3Privacy Invasion Used when someone enters without permission, showing disrespect for privacy. He burst in on her diary time, ignoring the 'Do Not Disturb' sign. Pro Tip 2/3Room Entry Often refers to entering a physical space like a room or building unexpectedly. During the party, a stranger burst in on the celebrations. Pro Tip 3/3Dramatic Effect The action creates drama or shock, used to highlight a sudden event. The police burst in on the scene just as the deal was about to go down.