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

Fermentation and distillation are tuned to produce a fruity, ester-rich spirit that can stand up to assertive casks. —Joseph V Micallef, Forbes.com, 26 May 2026

Gregg Renfrew’s newest product features hyaluronic acid and jojoba esters for a moisturizing dose of color. —Noor Lobad, Footwear News, 23 May 2026

But the company said competitors have used testosterone and testosterone esters, human growth hormones, stimulants like Adderall, metabolic modulators used alongside anabolic agents, erythropoietin, and anabolic steroid agents. —Kai Nicol-Schwarz, CNBC, 22 May 2026

Your Body Isn't Absorbing It The supplements in ethyl ester capsules are also poorly absorbed, reducing efficacy. —Ayesha Gulzar, Verywell Health, 6 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