• synonyms


[pi-rohl, pir-ohl]
noun Chemistry.
  1. a colorless, toxic, liquid, five-membered ring compound, C4H5N, that is a component of chlorophyll, hemin, and many other important naturally occurring substances.
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Origin of pyrrole

1825–35; irregular < Greek pyrr(hós) red + -ole2
Related formspyr·rol·ic [pi-rol-ik, -roh-lik] /pɪˈrɒl ɪk, -ˈroʊ lɪk/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for pyrrole

Historical Examples

  • This brings selenophene more akin to pyrrole than thiophene, but the group -NH- in the molecule of pyrrole is an auxochrome.

    Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives

    Y-Gwan Chen

British Dictionary definitions for pyrrole


  1. a colourless insoluble toxic liquid having a five-membered ring containing one nitrogen atom, found in many naturally occurring compounds, such as chlorophyll. Formula: C 4 H 5 NAlso called: azole
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Derived Formspyrrolic (pɪˈrɒlɪk), adjective

Word Origin

C19: from Greek purrhos red, from pur fire + -ole 1
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

pyrrole in Medicine


  1. A five-membered heterocyclic ring compound that has an odor similar to chloroform and is the parent compound of hemoglobin, chlorophyll, and many other complex, biologically active substances.imidole
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Related formspyr•rolic (pĭ-rōlĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

pyrrole in Science


  1. Any of a class of organic compounds having a five-member ring composed of four carbon atoms and one nitrogen atom. The pyrrole ring structure is a component of many biologically important compounds, including porphyrins, alkaloids, and certain amino acids.
  2. The simplest of this class of compounds, in which a single hydrogen atom is attached to each atom in the ring. It has a pleasant odor similar to that of chloroform. Chemical formula: C4H5N.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.