# cooperate

/ˈkwɑpɝˌeɪt/ (US) · /kəʊˈɒpəɹˌeɪt/ (UK)

Source: https://englishreference.com/word/cooperate
Updated: 2026-06-20

## Senses

### 1. to work together

verb · CEFR B1

to work with other people to reach a common goal or finish a task.

For teachers: to act or work jointly with others for a mutual benefit or common purpose.

- The two companies decided to cooperate on a new project to build electric cars.
- Local authorities and environmental groups must cooperate closely if they hope to restore the river's ecosystem within the next decade.

Usage: Usually followed by the preposition 'with' for people and 'on' for tasks.

### 2. to be helpful

verb · CEFR B2

to do what someone asks you to do, especially an official or a person in charge.

For teachers: to comply with the requests or instructions of others, particularly those in authority.

- The witness agreed to cooperate with the police and told them everything she saw.
- Despite initial hesitation, the suspect eventually chose to cooperate fully with the investigation in exchange for a reduced sentence.

Usage: Often used in the context of police investigations or following rules.

### 3. to function in harmony

verb · CEFR C1 · Literary

when things work well together to produce a good result.

For teachers: to function or operate in harmony; used of inanimate objects or abstract forces that align to produce a specific outcome.

- The weather did not cooperate, and our outdoor party was ruined by rain.
- For the experiment to succeed, every variable must cooperate perfectly, as even a minor fluctuation in temperature could invalidate the results.

### 4. to turn a witness

verb · CEFR C2 · Technical · American English

to persuade someone to help the police or a court, usually by offering them a deal.

For teachers: to obtain the formal assistance of a potential witness, often by offering legal incentives.

- The prosecutor spent months trying to cooperate the driver of the getaway car.
- Federal agents successfully cooperated the lead accountant, whose testimony provided the evidence needed to dismantle the entire criminal enterprise.

Usage: In this specific legal sense, the verb is used transitively.

## Examples

- The two companies decided to cooperate on the new project.
- The witness agreed to cooperate with the police in exchange for a lighter sentence.
- While the nations agreed to cooperate on environmental policy, the lack of a binding enforcement mechanism meant that individual compliance remained largely voluntary and inconsistent.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.