tredecillion

noun

tre·​de·​cil·​lion ˌtrē-di-ˈsil-yən 

often attributive

US : a number equal to 1 followed by 42 zeros see Table of Numbers

also, British : a number equal to 1 followed by 78 zeros see Table of Numbers

Word History

Etymology

Latin tredecim thirteen (from tres three + decem ten) + English -illion (as in million) — more at three, ten

First Known Use

1850, in the meaning defined above