noun, often attributive
un·​de·​cil·​lion | \ ˌən-di-ˈsil-yən \

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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to express emotion in a dramatic way

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