For alternate meanings, see: Accident (fallacy), Accident (philosophy), Accident (film), Accident, Maryland, and Car accidents.

An accident is a specific, identifiable, unexpected, unusual and unintented external event which occurs in a particular time and place, without apparent cause but with marked effect. It implies a generally negative probabilistic outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its occurrence.