Definition of QUINTILLION Merriam Websters.
US : a number equal to 1 followed by 18 zeros.
British : a number equal to 1 followed by 30 zeros.
Mark Twain : 2 or 3 infinities (also see unabridged dictionary).
First Known Use: 1674
Disclaimer: Mark Twain (1835-1910-To be continued) is unlicensed. His river pilot's license went delinquent in 1862. Caution advised. Daily Paul ☑