Source : Webster's Revised Unabridged Dictionary (1913)

Opium \O"pi*um\, n. [L., fr. Gr. ? poppy juice, dim. of ?
   vegetable juice.] (Chem.)
   The inspissated juice of the {Papaver somniferum}, or white
   poppy.

   Note: Opium is obtained from incisions made in the capsules
         of the plant, and the best flows from the first
         incision. It is imported into Europe and America
         chiefly from the Levant, and large quantities are sent
         to China from India, Persia, and other countries. It is
         of a brownish yellow color, has a faint smell, and
         bitter and acrid taste. It is a stimulant narcotic
         poison, which may produce hallicinations, profound
         sleep, or death. It is much used in medicine to soothe
         pain and inflammation, and is smoked as an intoxicant
         with baneful effects.

   {Opium joint}, a low resort of opium smokers. [Slang]

Source : WordNet®

opium
     n : an addictive narcotic extracted from seed capsules of the
         opium poppy