Tobacco - The prepared leaves of a tobacco plant, as used in cigarettes, cigars, and pipes.

Marijuana - The dried leaves and female flowers of the hemp plant, used in cigarette form as a narcotic or hallucinogen.

Hallucinogens - A drug or chemical that causes a person to have hallucinations. Mescaline, LSD, and psilocybin are hallucinogens.

Alcohol - whiskey, gin, vodka, or any other intoxicating liquor containing this liquid.

Inhalants - A medication, anesthetic, or other compound in vapor or aerosol form, taken by inhalation.

Vitamins - Any organic compounds that is needed in small amounts for normal growth and activity of the body.

Prescription drugs – Medicine that a doctor tells someone to take. These drugs are good for your body when taken exactly as the doctor says.

Some of these definitions are from http://www.dictionary.com.