Other forms: opiates
An opiate is a drug such as morphine or heroin that is derived from opium. Used figuratively, it means something that calms or soothes.
Karl Marx famously said that religion was the opiate of the masses, which means he thought that it was religion that prevented working-class people from rising up against their leaders. Today, you might say that television has replaced religion as a mass opiate, but you'd need to say that during a commercial for anyone to pay much attention.