酯(ester)
与水反应能生成醇和有机或无机酸的一类有机化合物的总称（参阅hydrolysis）。由羧酸衍生的酯最为常见，包括酸的羰基（carbonyl group，参阅functional group）；碳的第四个连结物为醇的氧原子。酯在硷存在下的水解，即所谓的皂化反应，被用来由脂和油制取肥皂，也用於酯的定量测定。低分子量的羧酸酯是带有香味的无色挥发性液体，微溶於水。许多酯是花和水果的芬芳和香味的来源。其他如醋酸乙酯和醋酸丁酯用作清漆、涂料和油漆的溶剂。酯还包括许多工业上重要的高分子聚合物。如卢西特（Lucite，聚甲基丙烯酸甲酯）和涤纶（Dacron，聚乙烯对苯二甲酸酯）。硫酸、磷酸和硝酸等无机酸也可和醇生成酯。磷酸酯是生物学上重要的物质（核酸〔nucleic acid〕即属於这一类），在工业上广泛用作溶剂、增塑剂、阻燃剂、汽油和油的添加剂以及杀虫剂。硫酸和亚硫酸的酯用於制造染料和药物。
English version：
ester
Any of a class of organic compounds that can react with water (see hydrolysis) to produce an alcohol and an organic or inorganic acid. They are formed by the reverse process, esterification: Acid reacts with alcohol to form an ester and water. Esters of carboxylic acids, the most common, contain the acid's carbonyl group (&singlehorzbond;C&doublehorzbond;O; see functional group); the carbon's fourth bond is with the alcohol's oxygen atom. Hydrolysis of esters in the presence of an alkali (saponification) is used to make soaps from fats and oils. Carboxylic acid esters of low molecular weight are colorless, volatile liquids with pleasant odors; they give flavor and fragrance to fruits and flowers and are used as synthetic flavors and fragrances. Others, such as ethyl acetate and butyl acetate, are used as solvents for lacquers, paints, and varnishes. Certain polymers are esters, including Lucite (polymethyl methacrylate), and Dacron (polyethylene terephthalate). Esters of alcohols and inorganic acids include nitrate esters (e.g., nitroglycerin), which are explosive; phosphate esters, including such biologically important compounds as nucleic acids; and others used as flame retardants, solvents, plasticizers, gasoline and oil additives, and insecticides.