Thymol, C10H14O, is a natural monoterpenoid phenol derivative of p-Cymene, isomeric with carvacrol, found in oil of thyme, and extracted from Thymus vulgaris, ajwain, and various other plants as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. Thymol also provides the distinctive, strong flavor of the culinary herb thyme, also produced from T. vulgaris. Thymol is only slightly soluble in water at neutral pH, but it is extremely soluble in alcohols and other organic solvents. It is also soluble in strongly alkaline aqueous solutions due to deprotonation of the phenol. Its dissociation constant (pKa) is 10.59±0.10. Thymol absorbs maximum UV radiation at 274 nm.

Thyme is a culinary herb consisting of the dried aerial parts of some members of the genus Thymus of flowering plants in the mint family Lamiaceae. Thymes are native to Eurasia and north Africa. Thymes have culinary, medicinal, and ornamental uses. The species most commonly cultivated and used for culinary purposes is Thymus vulgaris, native to SE Europe.