The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

   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.
         [1913 Webster]

   Opium joint, a low resort of opium smokers. [Slang]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

opianine \o"pi*a*nine\, n. (Chem.)
   An alkaloid (C22H23NO7) found in small quantity in opium.
   It is identical with narcotine. It is present in amounts up
   to 11% in Papaver somniferum, and is used clinically as an
   antitussive. --MI11

   Syn: noscapine; narcosine; opian.
        [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Poppy \Pop"py\, n.; pl. Poppies. [OE. popy, AS. popig, L.
   papaver.] (Bot.)
   Any plant or species of the genus Papaver, herbs with showy
   polypetalous flowers and a milky juice. From one species
   (Papaver somniferum) opium is obtained, though all the
   species contain it to some extent; also, a flower of the
   plant. See Illust. of Capsule.
   [1913 Webster]

   California poppy (Bot.), any yellow-flowered plant of the
      genus Eschscholtzia.

   Corn poppy. See under Corn.

   Horn poppy, or Horned poppy. See under Horn.

   Poppy bee (Zool.), a leaf-cutting bee (Anthocopa
      papaveris) which uses pieces cut from poppy petals for
      the lining of its cells; -- called also upholsterer bee.


   Prickly poppy (Bot.), Argemone Mexicana, a
      yellow-flowered plant of the Poppy family, but as prickly
      as a thistle.

   Poppy seed, the seed the opium poppy (Papaver
      somniferum).

   Spatling poppy (Bot.), a species of Silene (Silene
      inflata). See Catchfly.
      [1913 Webster] Poppy

WordNet (r) 3.0 (2006):

Papaver somniferum
    n 1: southwestern Asian herb with greyish leaves and white or
         reddish flowers; source of opium [syn: opium poppy,
         Papaver somniferum]