undecillion

noun

un·​de·​cil·​lion ˌən-di-ˈsil-yən 

often attributive

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

Word History

Etymology

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

First Known Use

1844, in the meaning defined above