违约 (wéi yuē): 약속을 깨뜨리다.

After signing the contract, he went back on his word, so the company took him to court, saying he had breached the agreement.

The landlord promised to rent to us for three years, but after only one year he asked us to move out—this is clearly a breach of contract.

She promised to keep the secret, but she told others about it; I think she broke her promise.

If Party B fails to deliver on time, it must bear liability for breach of contract and compensate Party A for its losses.

He defaulted multiple times, his credit record got worse and worse, and now he can't even get a bank loan.

Because the other party breached the contract, we had to cancel the entire cooperation plan and look for new partners.