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in·va·lid 1 (ĭnvə-lĭd)
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n.
One who is incapacitated by a chronic illness or disability.
adj.
1. Incapacitated by illness or injury.
2. Of, relating to, or intended for invalids.
tr.v. in·va·lid·ed, in·va·lid·ing, in·va·lids
1. To incapacitate physically.
2. Chiefly British To release or exempt from duty because of ill health: "I was not quite sick enough to be invalided out, even though I was of no more use" (Mary Lee Settle).
[From INVALID2 (influenced by French invalide, sickly, infirm).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 
in·val·id 2 (ĭn-vălĭd)
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adj.
1. Not legally or factually valid; null: an invalid license.
2. Falsely based or reasoned; faulty: an invalid argument.
[Latin invalidus, weak : in-, not; see IN-1 + validus, strong (from valēre, to be strong; see wal- in the Appendix of Indo-European roots).]
in′va·lidi·ty (-və-lĭdĭ-tē) n.
in·valid·ly adv.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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:

    Indo-European Roots

    Semitic Roots

    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.

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