salicylic acid, also called ortho-hydroxybenzoic acid, a white, crystalline solid that is used chiefly in the preparation of aspirin and other pharmaceutical products. The free acid occurs naturally in small amounts in many plants, particularly the various species of Spiraea. The methyl ester also occurs widely in nature; it is the chief constituent of oil of wintergreen. Salicylic acid was first prepared by the Italian chemist Raffaele Piria in 1838 from salicylaldehyde. In 1860 the German chemists Hermann Kolbe and Eduard Lautemann discovered a synthesis based on phenol and carbon dioxide. Today the compound is made from dry sodium phenoxide ... (100 of 278 words)