alkaloid Syllabification: (al·ka·loid)Pronunciation: /ˈalkəˌloid/Definition of alkaloid noun Chemistry any of a class of nitrogenous organic compounds of plant origin that have pronounced physiological actions on humans. They include many drugs (morphine, quinine) and poisons (atropine, strychnine). Origin: early 19th century: coined in German from alkalialkaloid in other Oxford dictionaries Definition of alkaloid in the British & World English dictionary
