# ascertain

/ˌæsɝˈteɪn/ (US) · /ˌæsətˈeɪn/ (UK)

Source: https://englishreference.com/word/ascertain
Updated: 2026-08-27

## Senses

### 1. to find out facts

verb · CEFR C1 · Formal

to find out the true facts about a situation or a piece of information.

For teachers: to discover or determine something with certainty; to establish a fact through investigation.

- The police are trying to ascertain the cause of the fire.
- The committee conducted a thorough investigation to ascertain whether the safety protocols had been followed correctly during the emergency.

Usage: This verb is transitive and requires a direct object, often a 'that' clause or a 'whether' clause.

Teaching tip: This is a high-register word; in everyday conversation, native speakers usually prefer 'find out' or 'check'.

### 2. to make sure

verb · CEFR C2 · Archaic · Formal

to make sure that something happens or is true.

For teachers: to ensure or make certain of an outcome or a fact.

- The contract was written to ascertain that both parties received equal payment.
- The ancient laws were designed to ascertain the rights of the landowners against any claims from the crown.

Usage: In modern English, this sense is almost entirely replaced by 'ensure' or 'guarantee'.

Teaching tip: Learners should be aware of this sense in older literature but avoid using it in modern business or academic writing.

## Examples

- We need to ascertain the cause of the problem.
- The police are still trying to ascertain the exact time the accident occurred by checking security cameras.
- Before the board can approve the merger, they must ascertain whether the company's current debts will impact long-term profitability.

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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.