[ poi-zuh-nuh s ]
/ ˈpɔɪ zə nəs /


full of or containing poison: poisonous air; a poisonous substance.
harmful; destructive: poisonous to animals; poisonous rumors.
deeply malicious; malevolent: poisonous efforts.

Origin of poisonous

First recorded in 1565–75; poison + -ous

Related forms

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

Examples from the Web for poisonous

British Dictionary definitions for poisonous


/ (ˈpɔɪzənəs) /


having the effects or qualities of a poison
capable of killing or inflicting injury; venomous
corruptive or malicious

Derived Forms

poisonously, adverbpoisonousness, noun
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

Medicine definitions for poisonous


[ poizə-nəs ]


Relating to or caused by a poison.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.