Ester
From Webster:
es·ter Pronunciation: 'es-t&r Function: noun. Etymology: German, from Essigäther ethyl acetate, from Essig vinegar + Äther ether. 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 with elimination of water.
Esters are flavor and aromatic compounds that contribute to the flavor profile of whiskeys, rums, and brandies. They can be detected at very low levels as in Parts Per Million/Billion in some cases. Many esters have distinctive fruit-like odors, and many occur naturally in the essential oils of plants. This has also led to their commonplace use in artificial flavorings and fragrances when those odors aim to be mimicked.