# ext

CEFR B1 · Noun

Source: https://englishreference.com/word/ext
Updated: 2026-05-08

## Definition

a short way of writing the word 'extension'. You see this most often in phone numbers or at the end of computer files.

For teachers: a standard abbreviation for 'extension'. Refers to an internal telephone line or a suffix at the end of a computer file name.

## Examples

- Call me at 555-0199, ext. 42.
- The receptionist asked for the specific ext. to direct the call to the accounting department.
- When configuring the server, ensure that the file ext. is correctly mapped to the appropriate application to prevent execution errors.

## Usage notes

- Typically written with a period (ext.) when used as an abbreviation in formal or business contexts.

---

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.