Definition of septillion in English:

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Pronunciation: /sepˈtilyən/

cardinal number (plural septillions or (with numeral) same)

1A thousand raised to the eighth power (1024). Compare with quadrillion.
Example sentences
  • This is a septillion times longer than the current age of the universe.
  • Translated into arithmetical terms, the result is 79 octillion, 228 septillion, 162 sextillion, 514 quintillion, 270 quadrillion with 15 zeros attached; that is 79,228,162,270,000,000,000,000,000.
  • Naturally occurring wormholes, if they exist at all, are likely to be extremely small, about 10 septillion times smaller than a typical atom.
1.1 dated, chiefly British A million raised to the seventh power (1042).


Late 17th century: from French, from million, by substitution of the prefix septi- 'seven' (from Latin septimus 'seventh') for the initial letters.

Words that rhyme with septillion

billion, jillion, million, bajillion, modillion, multibillion, multimillion, pillion, sextillion, squillion, trillion, zillion

For editors and proofreaders

Syllabification: sep·til·lion

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