# ester

/ˈɛstɝ/ (US) · /ˈɛstɐ/ (UK) · CEFR C2 · Noun

Source: https://englishreference.com/word/ester
Updated: 2026-08-15

## Definition

a chemical compound that often has a pleasant, fruity smell. You find these in nature in fruits and flowers, and they are also used to make artificial flavors and perfumes.

For teachers: an organic compound formed by the reaction between an acid and an alcohol, typically with the elimination of water. Characterised by a carbon atom double-bonded to an oxygen atom and single-bonded to an alkoxy group.

## Examples

- The sweet smell of a banana comes from an ester.
- Chemists often synthesise specific esters in the lab to create artificial scents for soaps and candles.
- In organic chemistry, the process of esterification involves a carboxylic acid reacting with an alcohol in the presence of an acid catalyst to produce an ester and water.

## Usage notes

- Often used in the plural when referring to a class of compounds or various scent profiles.

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