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un·de·cil·lion

(un′dĭ-sĭlyən)

1. The cardinal number equal to 10³⁶.

2. Chiefly British The cardinal number equal to 10⁶⁶.

[Latin undecim, ūndecim (ūnus, one; see oi-no- in the Appendix of Indo-European roots + decem, ten; see dek in the Appendix of Indo-European roots) + (M)ILLION.]

un′de·cillion adj.

un′de·cillionth adj., adv. & n.

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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