1 breach of the law/rules/agreement etc an action that breaks a law, rule, or agreement between people, groups, or countries: a clear breach of the 1994 Trade Agreement | be in breach of sth: We will expel any member found to be in breach of the rules. | breach of contract: If they fail to deliver the goods, we will sue them for breach of contract.2 breach of confidence/trust/etiquette etc an action that breaks the rules of what people consider good or moral behaviour: Bond shook the Queen's hand in a deliberate breach of etiquette. | The company regards revealing confidential information as a serious breach of trust.3 (C) a serious disagreement between people, groups, or countries with the result that they do not have a good relationship any more: Britain could not risk a breach with the US over sanctions. | heal the breach (=make people etc stop disagreeing and be friends again)4 breach of the peace BrE law an action such as fighting that annoys people in a public place5 step into the breach to help by doing someone else's job or work when they are suddenly unable to do it6 (C) a hole or broken place in a wall or similar structure, especially one made during a military attack: a breach in the castle wall7 a breach of security/duty etc the result of someone breaking a system, not doing their duty etc: There had been a major breach of security at the air base.2 verb (T)1 to break a hole in a wall or similar structure so that something can pass through: The storm had breached the sea wall in two places.2 to break a law, rule, agreement etc: The committee ruled that Payne was guilty of breaching the rules on sponsorship.
Longman dictionary of contemporary English. 2004.