prefix co

Meanings

1. 1prefix

   Added to nouns and verbs to mean doing something together with another person or group.

   Grammar: Attaches to a noun or verb with a hyphen: co-author, co-produce. It cannot stand alone as a word in a sentence.

   Patterns

   • co- + noun (co-worker, co-founder)
   • co- + verb (co-write, co-produce)

   She is the co-author of a book on climate policy.

   The two companies agreed to co-produce the film.

   He became co-chair of the committee last spring.

2. 2prefix

   Used with words for jobs or positions to show that two or more people share the role equally.

   Grammar: Forms nouns naming a shared role: co-chair, co-captain, co-editor. The plural is made on the whole word: co-chairs.

   Patterns

   • co- + job noun (co-chair, co-captain)
   • co- + noun + of something

   They serve as co-editors of the journal.

   Maya was named co-captain of the team.

   The co-chairs opened the meeting together.

3. 3prefixtechnical

   Joined to words to show that something is connected with or happens at the same time as something else.

   Grammar: Often appears in fixed terms such as co-exist and co-occur; keep the hyphen before a vowel.

   Patterns

   • co- + verb (co-exist, co-occur)

   Different species can co-exist in the same forest.

   These two symptoms often co-occur in patients.

   The old and new systems co-existed for a year.

Common combinations

co-author

She asked her colleague to be a co-author on the paper.

co-founder

The co-founder left the startup after two years.

co-worker

My co-workers helped me move desks.

co-operate

The two schools co-operate on sports events.

co-exist

Wildlife and farmers can co-exist with careful planning.

co-chair

He was elected co-chair of the parents' group.

Synonyms and how they differ

joint

Use 'joint' as an adjective before a noun (a joint project) when you want a single word rather than a prefix.

together

This adverb describes the action, while co- is fixed onto a noun or verb to build a new word.

fellow

'Fellow' describes the other person (a fellow worker), not the shared nature of the activity.

Word family

cooperation noun

The act of working together toward a shared aim.

cooperative adjective

Willing to help and work with others.

coordinate verb

To organize people or activities so they work well together.

Commonly confused: prefix co or co?

Practice

Make it your own

Write a sentence using “prefix co”, then check it and compare it with the examples above.

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