a gap in a wall, barrier, or defence, especially one made by an attacking army
They held back the enemy despite the breach of a critical gate.
a serious disagreement or break in relations between people, groups, or countries
Article 45 deals with the breach of relations between States.
an act of unauthorized entry into, or corruption of, information stored on computer, especially by a hacker or as part of a cyber attack
The company has taken further measures to protect customer data since the breach.