The Oxford Thesaurus An A-Z Dictionary of Synonyms - occurrencen.

1) happening, event, incident, phenomenon, affair, matter, experience: Earthquakes are frequent occurrences in California. 2 existence, instance, manifestation, materialization, appearance, development: The occurrence of mutations diversifies the species. 3) frequency, incidence, rate; likelihood, chance: What is the recorded occurrence of typhoons in the South China Sea?