A cyclic terpene, C₁₀H₁₆, used in perfumery and as a flavouring. It exists in three isomeric forms. α‎-Terpinene is an oily liquid that smells of lemons, b.p. 182°C. It occurs in the herbs cardamom, coriander and marjoram although it is usually extracted from the essential oils of other plants. β‎-Terpinene, b.p. 174°C, is generally synthesized from oil of savin. γ‎-Terpinene, b.p. 182°C, occurs in various plant oils, including those of coriander, cumin, lemon, and samphire. It can be made by the action of an alcoholic sulphuric acid solution on pinene (the major component of turpentine).