alkaloid

American  

[al-kuh-loid] / ˈæl kəˌlɔɪd /

noun

1. 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 combine with acids without the loss of a water molecule to form water-soluble hydrochlorides, hydrobromides, or the like, and that usually exhibit pharmacological action, as nicotine, morphine, or quinine.

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adjective

1. resembling an alkali; alkaline.

alkaloid British  

/ ˈælkəˌlɔɪd /

noun

1. 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

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alkaloid Scientific  

/ ăl′kə-loid′ /

1. Any of a large class of naturally occurring, complex organic compounds that contain nitrogen and have physiological effects on animals, including humans. Most alkaloids occur in plants, although some are produced by fungi and animals. Alkaloids are bases and usually form colorless crystalline solids with a bitter taste. They have a wide range of effects and are used as medicines and poisons. Morphine, quinine, strychnine, codeine, caffeine, cocaine, and nicotine are all alkaloids.

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Other Word Forms

• nonalkaloid noun

Etymology

Origin of alkaloid

First recorded in 1825–35; alkal(i) + -oid

Example Sentences

Researchers at the University of York focused on a plant known as Flueggea suffruticosa, which makes a strong alkaloid called securinine.

From Science Daily • Feb. 3, 2026

It was backed by the Global Kratom Coalition, whose executive director, Matthew Lowe, argued kratom products should have an alkaloid content similar to the natural plant that has long been used.

From Los Angeles Times • Aug. 15, 2024

He said the medical cause of Benn's death was "refractory cardiogenic shock due to taxane alkaloid poisoning, following ingestion of yew tree berries and leaves".

From BBC • Dec. 4, 2023

Eventually we found a very strong link between a change in alkaloid levels and a variation of a single sequence in our gene.

From Salon • Oct. 2, 2023

And R. leguminicola, it turns out, is a variety of mold that produces a potent alkaloid called swainsonine—a compound well known to ranchers and veterinarians as a killer of livestock.

From "Into the Wild" by Jon Krakauer