Real Dictionary

alkaloid in American English
any of a number of heterocyclic, colorless, crystalline, bitter organic substances, such as caffeine, morphine, quinine, and strychnine, having alkaline properties and containing nitrogen: they are found in plants and, sometimes, animals, and are used as
adjective: resembling an alkali; alkaline
noun: any of a large class of organic, nitrogen-containing ring compounds of vegetable origin and sometimes synthesized, some of which are liquid but most of which are solid, that have a bitter taste, that are usually water-insoluble and alcohol-soluble, that c

alkaloid in British English
noun: any of a group of nitrogenous basic compounds found in plants, typically insoluble in water and physiologically active. Common examples are morphine, strychnine, quinine, nicotine, and caffeine

alkaloid in the Pharmaceutical Industry
noun: Alkaloids are nitrogenous (= containing nitrogen or a nitrogen compound) plant substances, for example, belladonna, ergot, and vinca, used in drugs.