An unsafe act is a behavior or action that has the potential to cause harm or injury to oneself or others. 

Risk is the likelihood of a specific undesired event occurring with in specified period. R=P *S

An event did not result in an accident

Near Miss

Accident is an unexpected event

Accident

Injury that result in death, loss of consciousness

Injury

An unsafe condition is a situation  that has the potential to cause harm or injury to people, damage to property, environment.