Delta(9)-tetrahydrocannabinol is a diterpenoid that is 6a,7,8,10a-tetrahydro-6H-benzo[c]chromene substituted at position 1 by a hydroxy group, positions 6, 6 and 9 by methyl groups and at position 3 by a pentyl group. The principal psychoactive constituent of the cannabis plant, it is used for treatment of anorexia associated with AIDS as well as nausea and vomiting associated with cancer chemotherapy. It has a role as a metabolite, a non-narcotic analgesic, a hallucinogen, a cannabinoid receptor agonist and an epitope. It is a diterpenoid, a benzochromene, a polyketide and a phytocannabinoid.