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  1. a pathogen, especially one used in or produced by biological research.
  2. the health risk posed by the possible release of such a pathogen into the environment.

Origin of biohazard

Related formsbi·o·haz·ard·ous, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for biohazardous


  1. material of biological origin that is hazardous to humans
Derived Formsbiohazardous, adjective
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 biohazardous



also bio-hazard, 1973, from bio- + hazard (n.).

Online Etymology Dictionary, © 2010 Douglas Harper

biohazardous in Medicine


  1. A biological agent, such as a virus or a condition that constitutes a threat to humans, especially in biological research or experimentation.
  2. The potential danger or harm from exposure to such an agent or condition.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

biohazardous in Science


  1. A biological agent, such as an infectious microorganism, that constitutes a threat to humans or to the environment, especially one produced in biological research or experimentation.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.