A green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of a plant. You may hear marijuana called by street names such as pot, herb, weed, grass, boom, Mary Jane, gangster, or chronic. There are more than 200 slang terms for marijuana. Sinsemilla (sin-seh-me-yah; it's a Spanish word), hashish ("hash" for short), and hash oil are stronger forms of marijuana. All forms of marijuana are mind-altering. In other words, they change how the brain works. They all contain THC (delta-9- tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals. Marijuana's effects on the user depend on the strength or potency of the THC it contains. THC potency of marijuana has increased since the 1970s but has been about the same since the mid-1980s.
Cannabis, (also known as marijuana,"pot," "weed," "grass," or ganja in its herbal form and hashish in its resinous form) is a psychoactive product of the plant Cannabis sativa L. subsp. indica (= C. indica Lam.). The herbal form of the drug consists of dried mature inflorescences and subtending leaves of pistillate ("female") plants. The resinous form consists primarily of glandular trichomes collected from the same plant material.*source www.Wikipedia.org and http://workplace.samhsa.gov/Glossary/glossary.aspx