Related Clues:

• Opium, e.g.
• Addictive narcotic
• Sleep-inducing drug
• It'll put you under
• Drug that's a downer
• Calming agent
• Poppy-sap drug
• Morphine or codeine
• Heroin, for one
• Morphine or codeine, e.g.
• Religion, to Marx
• Religion, to the masses, per Marx
• Deadening agent
• What might be a knockout?
• A sedative drug