undecillion

American  

[uhn-di-sil-yuhn] / ˌʌn dɪˈsɪl jən /

noun

• undecillions,
  plural
• undecillion
  plural

1. a cardinal number represented in the U.S. by 1 followed by 36 zeros, and in Great Britain by 1 followed by 66 zeros.

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adjective

1. amounting to one undecillion in number.

Usage

What does undecillion mean?  In the United States, undecillion is the name of the number 1,000,000,000,000,000,000,000,000,000,000,000,000, or 10³⁶. In Great Britain, an undecillion is the name of a number represented by 1 followed by 66 zeroes, or 10⁶⁶. Because 1 undecillion is such a large number, you won’t often see it used. One of the most notable uses of undecillion is in the study of atoms. The ratio of electric force to gravitational force between two protons is roughly equal to one undecillion. Another notable use is in computing and internet infrastructure discussions. Under internet protocol version 6 (IPv6), the maximum number of IP addresses the global protocol can contain is around 340 undecillion. You’re more likely to see undecillion used figuratively to mean a large unknown amount, as in There are, like, 40 undecillion flavor choices, and I can’t decide!Example: This code cipher has over 1 undecillion possible combinations, making it nearly impossible to decode.

Other Word Forms

Derived Forms

• undecillionth
  adjective

Inflected Forms

Nouns

• undecillion
  plural
• undecillions
  plural

Etymology

Origin of undecillion

1930–35; < Latin undec ( im ) eleven ( ūn ( us ) one + -decim, combining form of decem ten ) + -illion, as in million

Example Sentences

See Examples For:

undecillion

The fine was for two undecillion roubles - more than the world's total GDP.

From BBC ● Jul. 2, 2026

The new IPv6, however, comes with 340 undecillion IP addresses — that’s 340 trillion trillion trillion.

From Washington Times ● Oct. 20, 2021

For example, “nomonkeyisnotagoodpassword” would take a computer 128 undecillion years to crack.

From The Guardian ● Mar. 28, 2018

The leap from IPv4 to v6 takes us from 4.3 billion addresses to 340 undecillion.

From Forbes ● Feb. 4, 2011

"An undecillion is ten raised to the 36th power," Freddy sighed, fearing that he wasn't getting through to Willy.

From Master of None by Neil Goble