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 drugs and stimulants, but can have a strong toxic effect on the human or animal system
Origin of alkaloidalkal(i) + -oid
Any of various organic compounds that are usually basic and contain at least one nitrogen atom in a heterocyclic ring, occurring chiefly in flowering plants. Many alkaloids, such as nicotine, quinine, cocaine, and morphine, are known for their poisonous or medicinal attributes.
Origin of alkaloidalkal(i) -oid
(comparative more alkaloid, superlative most alkaloid)
- Relating to, resembling, or containing alkali.
alkali + -oid. Compare French alcaloïde.