es·ter 
(ĕstər)
(ĕstər)n.
Any of a class of compounds derived from an oxyacid, usually resulting from the reaction of an oxyacid and an alcohol with the elimination of water.
[German, short for Essigäther : Essig, vinegar (from Middle High German ezzich, from Old High German ezzīh, from Latin acētum; see ak- in the Appendix of Indo-European roots) + Äther, ether (from Latin aethēr; see ETHER).]