Event

An incident or occurrence, from sources internal or external to an entity, that affects achievement of objectives.

Source : COSO Integrated Risk Management Framework

Occurrence or change of a particular set of circumstances.

Note 1: Nature, likelihood and consequence of an event cannot be fully knowable.
Note 2: An event can be on ore more occurrences, and can have several causes.
Note 3: Likelihood associated with the event can be determined.
Note 4: An event can consist of a non-occurrence of one or more circumstances.
Note 5: An event with a consequence is sometimes referred to as an "incident".
Note 6: An event where no loss occurs may also be referred to as a "near-miss", "near-hit", "close call" or "dangerous occurrence"

Source : BS31100:2008 [ISO Guide 73]