breach

If you breach a duty, you do something that you should not do.

If an army or the police breach a barrier, a wall, etc., they were not able to enter it before but now they can.

Example: The police breached the front door and searched the house.

A breach is the act of breaching; for example, a breach of contract may occur when somebody does not do what they promised.

A breach can also be a hole.

Example: Water entered through a breach in the levee.