alkaloid

[al-kuh-loid]Biochemistry, Chemistry, Pharmacology

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 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.

adjective

resembling an alkali; alkaline.

Origin of alkaloid

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

Related formsnon·al·ka·loid, noun, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for alkaloid

Historical Examples of alkaloid

Within the room Mr. Alkaloid was photographing the dead poodle.
Punch, or the London Charivari, Vol. 98 February 15, 1890
Various
Mr. Alkaloid had come from Ryde to London to get his hair singed.
Punch, or the London Charivari, Vol. 98 February 15, 1890
Various
This alkaloid is a white solid and is of great service in medicine.
An Elementary Study of Chemistry
William McPherson
It was but for a moment, for the action of the alkaloid is rapid.
A Study In Scarlet
Arthur Conan Doyle
Picrotoxin (C30H24O13) is not an alkaloid as may be seen from its formula.
The Medicinal Plants of the Philippines
T. H. Pardo de Tavera

British Dictionary definitions for alkaloid

alkaloid

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

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for alkaloid

1831, from alkali (q.v.) + -oid. "A general term applied to basic compounds of vegetable origin, bitter in taste, and having powerful effects on the animal system" [Flood]. As an adjective by 1859.

Medicine definitions for alkaloid

alkaloid

[ăl′kə-loid′]

n.

Any of various organic compounds, such as nicotine and morphine, that have basic chemical properties and that usually contain at least one nitrogen atom in a heterocyclic ring.

Science definitions for alkaloid

alkaloid

[ăl′kə-loid′]

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.