1. Great warmth and intensity of emotion. See Synonyms at passion.
2. Intense heat.
[Middle English fervour, from Old French, from Latin fervor, from fervēre, to boil; see bhreu- 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.