1. Weak in body or mind, especially from old age or disease. See Synonyms at weak.
2. Not strong or stable; shaky: an infirm foundation.
3. Archaic Lacking firmness of will, character, or purpose; irresolute.
[Middle English infirme, from Old French, from Latin īnfirmus : in-, not; see IN-1 + firmus, strong, firm; see dher- in the Appendix of Indo-European roots.]
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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.