noun, often attributive
un·​de·​cil·​lion | \ ˌən-di-ˈsil-yən How to pronounce undecillion (audio) \

Definition of undecillion

US : a number equal to 1 followed by 36 zeros — see Table of Numbers also, British : a number equal to 1 followed by 66 zeros — see Table of Numbers

First Known Use of undecillion

1844, in the meaning defined above

History and Etymology for undecillion

Latin undecim eleven (from unus one + decem ten) + English -illion (as in million) — more at one, ten

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The first known use of undecillion was in 1844

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Cite this Entry

“Undecillion.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/undecillion?pronunciation&lang=en_us&dir=u&file=undeci01. Accessed 19 January 2020.

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What made you want to look up undecillion? Please tell us where you read or heard it (including the quote, if possible).


to insert between existing elements

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