Is it ensure, insure, or assure?
compound formed by an acid joined to an alcohol, 1852, coined in German in 1848 by German chemist Leoipold Gmelin (1788-1853), professor at Heidelberg. "[A]pparently a pure invention" [Flood], perhaps a contraction of or abstraction from Essigäther, the German name for ethyl acetate, from Essig "vinegar" + Äther "ether" (see ether).
Essig is from Old High German ezzih, from a metathesis of Latin acetum (see vinegar).
ester es·ter (ěs'tər)
Any of a class of organic compounds corresponding to the inorganic salts and formed from an organic acid and an alcohol, usually with the elimination of water.
An organic compound formed when an acid and an alcohol combine and release water. Esters formed from carboxylic acids are the most common, and have the general formula RCOOR', where R and R' are organic radicals. Esters formed from simple hydrocarbon groups are colorless, volatile liquids with pleasant aromas and create the fragrances and flavors of many flowers and fruits. They are also used as food flavorings. Larger esters, formed from long-chain carboxylic acids, commonly occur as animal and vegetable fats, oils, and waxes. Esters have a wide range of uses in industry.