Opium
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Opium is a narcotic created from the sap of the opium poppy.
Opium den
An opium den is referred to directly by Doctor Sherman Cottle while talking to Cally (TRS: "The Ties That Bind"). Such places were legalized in the decades prior to the First Cylon War (CAP: "Gravedancing").
The Dive Bar is an establishment in pre-Fall Caprica City that combines a bar and an opium den (CAP: "Rebirth").