Definition of "occur"

occur

/əˈkɜː/

verb
third-person singular simple present occurs, present participle occurring, simple past and past participle occurred
1. (intransitive) To happen or take place.
  Quotations
  And no use for anyone to tell Charles that this was because the Family was in mourning for Mr Granville Darracott […]: Charles might only have been second footman at Darracott Place for a couple of months when that disaster occurred, but no one could gammon him into thinking that my lord cared a spangle for his heir.
  1959, Georgette Heyer, chapter 1, in The Unknown Ajax
2. (intransitive) To present or offer itself.
3. (impersonal) To come or be presented to the mind; to suggest itself.
  Quotations
  Apparently it never occurs to them that you can't make rapid, drastic changes in the technology and the economy of a society without causing rapid changes in all other aspects of the society as well, […]
  1995, Theodore Kaczynski, Industrial Society and Its Future
4. (intransitive, sciences) To be present or found.