ester

noun

es·​ter ˈe-stər 

: any of a class of often fragrant organic compounds that can be represented by the formula RCOOR′ and that are usually formed by the reaction between an acid and an alcohol with elimination of water

Examples of ester in a Sentence

Recent Examples on the Web

There was one compound, an ester called isopropyl myristate, that scientists found in the samples taken from queens and nowhere else. — Jacek Krywko, ArsTechnica, 21 July 2026

Founded in 1753, the Jamaican distillery is famous for high-ester rums prized for their aromatic power and complexity. — Hudson Lindenberger, Forbes.com, 12 June 2026

Meanwhile bamboo water, jojoba esters, and two forms of hyaluronic acid help to impart hydration and calm skin. — Rosa Jisoo Pyo, Vogue, 31 May 2026

Among the 34 doping athletes who took part in the trial, 91% used testosterone or testosterone esters, 79% used human growth hormone, and 62% opted for stimulants such as Adderall. — Andrew Greif, NBC news, 26 May 2026

Word History

Etymology

German, from Essigäther ethyl acetate, from Essig vinegar + Äther ether

First Known Use

circa 1852, in the meaning defined above

Rhymes for ester

• esther
• fester
• jester
• nester
• nestor
• pester
• prester
• quaestor
• tester
• wester
• yester
• ancestor

Kids Definition

ester

noun

es·​ter ˈes-tər 

: an organic compound formed by the reaction between an acid and an alcohol

Medical Definition

ester

noun

es·​ter ˈes-tər 

: any of a class of often fragrant compounds that can be represented by the formula RCOOR′ and that are usually formed by the reaction between an acid and an alcohol usually with elimination of water