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thir·teen

(thûr-tēn)

1. The cardinal number that is equal to the sum of 12 + 1.

2. The 13th in a set or sequence.

3. Something having 13 parts, units, or members.

[Middle English thyrtene, alteration of thrittene, from Old English thrēotīne; see trei- in the Appendix of Indo-European roots.]

thir·teen adj. & pron.

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:

Indo-European Roots

Semitic Roots

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.

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