Marijuana is a psychoactive dried resinous flower buds and leaves of the female hemp or  cannabis plant, which contain high levels of THC. When smoked, vaped, or ingested, marijuana  can cause euphoria or relaxation, as well as anxiety, paranoia, and in extreme instances,  psychosis. Slang terms for marijuana include weed, pot, dope, grass, reefer, ganja, hash, MJ,  herb, chronic.