Share this entry

quadrillion Syllabification: quad·ril·lion
Pronunciation: /kwäˈdrilyən/

Definition of quadrillion in English:

cardinal number (plural quadrillions or (with numeral or quantifying word) same)

1A thousand raised to the power of five (1015).
Example sentences
  • The lesson continues this way up until the quadrillions.
  • Others are known that are so very slightly unstable that their half-lives are trillions and quadrillions of years.
  • Each of them had been coated with quadrillions of luminescent particles.
1.1 dated, chiefly British A septillion, that is, a thousand raised to the power of eight (1024).



Pronunciation: /-ˈdrilyənT͟H/
ordinal number
Example sentences
  • With the neutrons traveling much, much faster, I estimate about 28 percent of the material will go critical in that quadrillionth of a second.
  • In addition, LCLS X-ray pulses will be extremely short - lasting only femtoseconds, mere quadrillionths of a second.
  • A femtosecond is a millionth of a billionth (or one quadrillionth) of a second.


Late 17th century: from French, from million, by substitution of the prefix quadri- 'four' for the initial letters.

Definition of quadrillion in:

Share this entry


What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.

Get more from Oxford Dictionaries

Subscribe to remove ads and access premium resources