Al″ka‐loid (ăl″kȧ‐loid), n.(Chem.) An organic base, especially one of a class of substances occurring ready formed in the tissues of plants and the bodies of animals.
☞ Alkaloids all contain nitrogen, carbon, and hydrogen, and many of them also contain oxygen. They include many of the active principles in plants; thus, morphine and narcotine are alkaloids found in opium.