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

One of those, called organophosphate ester, or OPFRs, was measured in the new research. —Sandee Lamotte, CNN Money, 15 Apr. 2025

Bacterial fermentation can add desirable complexity to whiskey by producing lactic acid and esters. —Joseph V Micallef, Forbes.com, 26 Apr. 2025

The primer end of this dual-sided tube is infused with softening jojoba esters, helping your mascara swipe on more smoothly and evenly with maximum lash lengthening and separation. —Michelle Rostamian, Allure, 8 Apr. 2025

Jojoba esters add to its silky smooth application, while ginseng extract further reduces inflammation and boosts collagen production, leaving skin looking plump and radiant. —Conçetta Ciarlo, Vogue, 1 Apr. 2025

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