-logy or -ology
1. Discourse; expression: phraseology.
2. Science; theory; study: dermatology; sexology.
[Middle English -logie, from Old French, from Latin -logia, from Greek -logiā (from logos, word, speech; see leg- in the Appendix of Indo-European roots) and from -logos, one who deals with (from legein, to speak; see leg- 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.