1. an unexpected and undesirable event, especially one resulting in damage or harm
2. an event that happens by chance or without apparent cause

Examples

• She was injured in a car accident on the highway.
• The broken vase was just an accident – nobody meant to knock it over.
• Three people were taken to the hospital after the workplace accident.
• It was no accident that they met at the coffee shop every Tuesday.
• The discovery of penicillin happened by accident.
• Please report any accidents to your supervisor immediately.
• Their meeting was a happy accident that led to a lifelong friendship.