A highly infectious viral disease that chiefly affects children and, in its acute forms, causes inflammation of motor neurons of the spinal cord and brainstem, leading to paralysis, muscular atrophy, and often deformity. Through vaccination, the disease is preventable. Also called infantile paralysis, polio.
[Greek polios, gray (since it affects the gray matter); see pel-1 in the Appendix of Indo-European roots + MYELITIS.]
po′li·o·my′e·litic (-lĭtĭk) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.