A small mountain lake, especially one formed by glaciers.
[Introduced into Standard English by poets associated with the Lake District such as Coleridge, Southey, and Wordsworth, from dialectal English (northern England) tarn, tairn, upland pond or small lake, from Middle English terne, tarne, pond, from Old Norse tjǫrn; see der- 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.