What is the meaning of event?

noun

• Something that happens at a given place and time.
• A special set of circumstances.
  • usage: "in that event, the first possibility is excluded"; "it may rain in which case the picnic will be canceled"
  • synonyms: case
• A phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory.
• A phenomenon that follows and is caused by some previous phenomenon.
  • usage: "the magnetic effect was greater when the rod was lengthwise"; "his decision had depressing consequences for business"; "he acted very wise after the event"
  • synonyms: consequence, effect, outcome, result, issue, upshot