Incident:
1. an individual occurrence or event.
2. a distinct piece of action, or an episode, as in a story or play.
3. something that occurs casually in connection with something else.


in·ci·dence 
–noun
1. the rate or range of occurrence or influence of something, especially of something unwanted: the high incidence of heart disease in men over 40.
2. a falling upon, affecting, or befalling; occurrence: The incidence of murder that Sunday afternoon shocked the sleepy village.