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alkaloid

[al-kuh-loid]Biochemistry, Chemistry, Pharmacology
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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.
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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. 2018

Examples from the Web for alkaloid

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British Dictionary definitions for alkaloid

alkaloid

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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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

n.

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.

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Online Etymology Dictionary, © 2010 Douglas Harper

alkaloid in Medicine

alkaloid

(ălkə-loid′)
n.
  1. 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.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

alkaloid in Science

alkaloid

[ălkə-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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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.