1. Of, relating to, or caused by a toxin or other poison: a toxic condition; toxic hepatitis.
2. Capable of causing injury or death, especially by chemical means; poisonous: toxic industrial waste.
a. Extremely risky or harmful, as a debt for which the borrower is in default and the collateral has lost so much value that its sale cannot cover the amount of the loan.
b. Causing social tension or unpleasantness: a toxic personality.
A toxic chemical or other substance.
[Late Latin toxicus, from Latin toxicum, poison, from Greek toxikon, poison for arrows, poison, from neuter of toxikos, of a bow, from toxon, bow, from Old Persian *taxša-, an arrow.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.