1. A substance that causes injury, illness, or death, especially by chemical means.
2. Something destructive or fatal.
3. Chemistry A substance that inhibits another substance or a reaction: a catalyst poison.
tr.v. poi·soned, poi·son·ing, poi·sons
1. To kill or harm with poison.
2. To put poison on or into: poisoning arrows; poisoned the drink.
a. To pollute: Noxious fumes poison the air. See Synonyms at contaminate.
b. To have a harmful influence on; corrupt: Jealousy poisoned their friendship.
4. Chemistry & Physics To inhibit (a substance or reaction).
[Middle English, from Old French, from Latin pōtiō, pōtiōn-, drink; see pō(i)- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.