benzoic acid UK /bɛnˈzəʊɪk ˈasɪd/US /bɛnˈzoʊɪk ˈæsɪd/ noun1 •A white crystalline organic acid, C₆H₅COOH; the simplest aromatic carboxylic acid; used as a food preservative and in many other industrial applications. formsbenzoic acids