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  1. Pharmacology. dioxin.


noun Chemistry.
  1. a general name for a family of chlorinated hydrocarbons, C12H4Cl4O2, typically used to refer to one isomer, TCDD, a by-product of pesticide manufacture: a toxic compound that is carcinogenic and teratogenic in certain animals.
Compare Agent Orange.

Origin of dioxin

First recorded in 1965–70; di-1 + ox- + -in2
Also called TCDD
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for tcdd


  1. any of a number of mostly poisonous chemical by-products of the manufacture of certain herbicides and bactericides, esp the extremely toxic 2,3,7,8-tetrachlorodibenzo-para-dioxin
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 tcdd



1919, from dioxy- + chemical suffix -in (2). All the compounds in the group are characterized by two oxygen atoms.

Online Etymology Dictionary, © 2010 Douglas Harper

tcdd in Medicine


  1. Any of several carcinogenic or teratogenic heterocyclic hydrocarbons that occur as impurities in petroleum-derived herbicides.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

tcdd in Science


  1. Any of several toxic hydrocarbons that occur as impurities in petroleum-derived herbicides, disinfectants, and other products. Dioxins are composed of two benzene rings connected by two oxygen atoms, and the most familiar kind, called TCDD, has two chlorine atoms attached to each benzene ring. TCDD was once thought to cause cancer and birth defects, but subsequent research showed it to have only mild toxic effects except at very high exposure levels.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

tcdd in Culture



A group of pollutants created as by-products in many industrial processes. Dioxins accumulate in human tissue and affect human metabolism. They are carcinogens. Eliminating dioxins is an important goal of environmental policy.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.