quintillion

noun

quin·​til·​lion kwin-ˈtil-yən 

US : a number equal to 1 followed by 18 zeros see Table of Numbers

also, British : a number equal to 1 followed by 30 zeros see Table of Numbers

quintillion adjective

quintillionth

kwin-ˈtil-yən(t)th 

adjective or noun

Examples of quintillion in a Sentence

Recent Examples on the Web

These machines can crunch numbers at blinding speeds—more than a quintillion (that’s a one followed by 18 zeroes) operations a second—assuming they can be fed data fast enough. — Iain Martin, Forbes.com, 6 Aug. 2026

In certain metal samples, fusion occurred about a quintillion times—a 1 followed by 18 zeroes—more often than in reactions without a host material. — Aman Tripathi, Interesting Engineering, 26 July 2026

In 1946, Hungary replaced the pengö with a new currency—the forint—at a rate of 400 quintillion pengö to 1 forint, which eventually stabilized the economy. — Encyclopedia Britannica, 14 Apr. 2026

Both of these decay rapidly into even more particles, so in the end, ultrahigh-energy protons (with more than 50 quintillion eV) from distant galaxies should never reach us. — Phil Plait, Scientific American, 3 Apr. 2026

Word History

Etymology

Latin quintus + English -illion (as in million)

First Known Use

circa 1690, in the meaning defined above

Rhymes for quintillion

• castilian
• civilian
• cotillion
• pavilion
• postilion
• quadrillion
• reptilian
• vermilion
• vermillion
• billion
• million
• pillion

Kids Definition

quintillion

noun

quin·​til·​lion kwin-ˈtil-yən 

US : a number equal to 1 followed by 18 zeros see number

also, British : a number equal to 1 followed by 30 zeros see number