Breach - (noun and verb)
If an agreement or contract is breached, then one (or more) of the parties have broken the terms of the contract or agreement. The word can also be used as a noun. For example, ‘there was a breach of the contract’.
Source: Adapted from Collins Dictionary.
Example of Use: One of the main roles of the shop steward is to ensure that the employer doesn’t attempt to breach the terms of the collective agreement.