co-occur

IPA/ˌkəʊ əˈkɜː(r)/
IPA/ˌkəʊ əˈkɜːr/

co-occur — verb

  • co-occurpresent simple I / you / we / they
  • co-occurshe / she / it
  • co-occurredpast simple
  • co-occurring-ing form
  • co-occuredpast participle

1. when several events, situations, or natural processes happen together during a s

1.verbintransitiveB2
Definition

when several events, situations, or natural processes happen together during a shared moment or within a shared space, we say they co-occur

Example

Dr. Wei found that migraine headaches and sleep problems often co-occur in patients.

often co-occur + in [patient group / context]

In the Himalayan region, several medicinal herbs co-occur in the same high-altitude meadows.

co-occur + in [specific location]

Common collocations
  • frequently co-occur
  • co-occur with
  • often co-occur
  • commonly co-occur
  • rarely co-occur
  • co-occur naturally
  • co-occur in the same
Synonyms
  • coincide

    more precise for time, slightly more formal; less common for spatial co-occurrence

  • coexist

    focuses on peaceful or simultaneous existence, often of living things or ideas; stronger spatial than temporal sense

  • overlap

    suggests partial rather than full coincidence; common in scheduling and Venn-diagram contexts

  • happen together

    more basic, less formal; suitable for everyday conversation

Grammar Patterns

co-occur + with + noun phrase

co-occur + in + location/time phrase

co-occur + adverbial (often / rarely / frequently)

Usage Note

The subject is usually plural or compound — a single event or item cannot co-occur by itself. When focusing on two specific things, co-occur is typically followed by with.

Common Mistakes

The rain co-occurred the strong wind.
The rain co-occurred with the strong wind.
co-occur is intransitive and needs with to link the two elements.
The meeting co-occurred at 3 pm.
The meeting co-occurred with the training session at 3 pm.
a single event cannot co-occur alone.

Word family

Synonym discussion

Sense: verb/1

Coincide is the closest formal synonym for co-occur when the emphasis is on time — two events coincide if they happen at the same moment. Coexist shifts the focus to peaceful or harmonious existence in the same space, most often used for people, species, or ideas rather than events. Overlap suggests partial rather than full coincidence and is common in scheduling, graphs, and research findings (e.g. "the symptoms overlapped"). Happen together is the plain, everyday alternative that learners can use in conversation without worrying about register. For example, you would write "the conference co-occurred with the festival" in a report, but tell a friend "the party and the concert happened together last weekend."

coincide ↗coexist ↗overlap ↗happen together

Common collocations

Nouns

Adverbs

Phrases

Prepositions

Etymology

LatinEnglish

Formed from the prefix co- ('together', from Latin cum) and the verb occur ('to happen, to be met with', from Latin occurrere, literally 'to run toward'). The word entered English in scientific and academic writing during the late 19th century to describe events or natural phenomena that share a time or place.

First known use

1957

1957, in the meaning defined above