当事人 (dāng shì rén): persons involved or implicated; party (to an affair)

After the traffic accident occurred, the traffic police quickly arrived at the scene and separately questioned the two parties involved about what had happened.

During the divorce mediation, the mediator patiently listened to the demands of both parties involved, hoping to help them reach an agreement acceptable to both.

This contract not only requires the company representative's signature but also the personal signatures of all relevant parties involved; otherwise, it has no legal effect.

The reporter interviewed several parties involved in the accident, asking them to describe what happened at the time so that the public could understand the truth.