An anesthetic is a substance used to reduce or eliminate sensation, usually for medical purposes. Painkillers, soporifics, opiates, hypnotics, anodynes, analgesics, narcotics, drugs, gases, and ethers are all types of anesthetics. Painkillers are substances that reduce or eliminate pain, soporifics induce sleep, opiates are drugs derived from opium, hypnotics are drugs that induce sleep, anodynes are substances that reduce pain, analgesics are drugs that reduce pain without causing loss of consciousness, narcotics are drugs that induce sleep and reduce pain, drugs are substances used to treat illnesses, gases are substances in the air, and ethers are volatile organic compounds.