a. Incapable of moving or acting: "[Some patients] lingered, unable to breathe on their own, inert and unresponsive even to the most noxious stimulus" (Gary Greenberg).
b. Sluggish in action or motion; lethargic. See Synonyms at inactive.
2. Chemistry Not readily reactive with other elements; forming few or no chemical compounds.
3. Having no pharmacologic, metabolic, or other physiological effect.
[Latin iners, inert- : in-, not; see IN-1 + ars, skill; see ar- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.