1. Causing or capable of causing death: a lethal weapon. See Synonyms at fatal.
2. Extremely harmful; devastating: accusations lethal to the candidate's image.
[Late Latin lēthālis, alteration (probably influenced by Lēthē, Lethe) of Latin lētālis, from lētum, death.]
le·thali·ty (lē-thălĭ-tē) n.
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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.