Opiate

n. [N. Lat. opiatum, from Lat. opium; Fr. opiat, Sp. op iado, It. oppiato. See OPIUM.]

1. Originally, a medicine of a thicker consistence than syrup, prepared with opium. Parr.
2. Any medicine that contains opium, and has the quality of inducing sleep or repose; a narcotic.
3. That which induces rest or inaction; that which quiets uneasiness.

They chose atheism as an opiate. Bentley.

a. [It. oppiato, Sp. op iado. See OPIUM.]

1. Inducing sleep; soporiferous; somniferous; narcotic.
2. Hence, causing rest or inaction.