morphine

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A bitter crystalline alkaloid, C₁₇H₁₉NO₃·H₂O, extracted from opium, the soluble salts of which are used in medicine as an analgesic, a light anesthetic, or a sedative.

from The Century Dictionary.

• noun An alkaloid, C₁₇H₁₉N0₃, the most important narcotic principle of opium.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Chem.) A bitter white crystalline alkaloid found in opium, possessing strong narcotic properties, and much used as an anodyne; -- called also morphia, and morphina.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A crystalline alkaloid (7,8-didehydro-4,5-epoxy-17-methyl-morphinan-3,6-diol), extracted from opium, the salts of which are soluble in water and are used as analgesics, anaesthetics and sedatives; it is one of a group of morphine alkaloids.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an alkaloid narcotic drug extracted from opium; a powerful, habit-forming narcotic used to relieve pain