occur

 
Pronunciation: /əˈkəː/

verb (occurs, occurring, occurred)

[no object, with adverbial]
  • happen; take place: the accident occurred at about 3.30 p.m.
  • exist or be found to be present in a place or under a particular set of conditions: radon occurs naturally in rocks such as granite
  • (occur to) (of a thought or idea) come into the mind of: [with clause]: it occurred to him that he hadn’t eaten

Origin:

late 15th century: from Latin occurrere 'go to meet, present itself', from ob- 'against' + currere 'to run'

Spelling rule

If a verb ends with a single vowel plus a consonant, and the stress is at the end of the word (as in refer), double the last letter when adding endings which begin with a vowel: (occurs, occurring, occurred).