What does octillion mean?
An octillion is an enormous named number used chiefly in mathematics, science, and hypothetical calculations. Its value depends on the numbering system: in the short scale used in the United States, it equals 10^27, while in the long scale used in Britain and many other countries, it equals 10^48. The difference is so substantial that an octillion can refer to either a billion billion or a vastly larger magnitude. The word is normally used when precision and rhetorical scale matter, as in estimates of search-space size, possible outcomes, or astronomically long durations. Because the same magnitude may receive a different name under the long scale, readers should check which convention is intended. Despite its extreme value, the term remains useful for describing theoretical quantities beyond the practical range of ordinary numbers.
nounA named large number equal to 10^27 in the short scale used in the United States, or 10^48 in the long scale used in Britain. The word chiefly appears in scientific, mathematical, or hypothetical contexts.
- A named number equal to 10^27 under the short-scale naming system or 10^48 under the long-scale naming system.
"The calculation required an octillion possible configurations before the researchers found the correct sequence."
"Even at a rate of a billion searches per second, checking every possible sequence would take more than an octillion years."
"The philosopher used the number an octillion to illustrate the limits of human comprehension."
The plural is used when referring to multiple quantities or instances of that magnitude.
"The simulations involved several octillions of possible arrangements."
One octillion can mean 10^27 or 10^48, depending on which side of the Atlantic you ask.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does octillion come from?
The word entered English in the 17th century from French octillion, a term formed from Latin octo, meaning “eight,” and million. Its name originally reflected the number of groups of a million in the naming system then used in continental Europe. Short-scale and long-scale traditions subsequently diverged, producing the different numerical values associated with the word today.
How octillion is actually used
This is a formal term used primarily in mathematical, scientific, and speculative contexts. Because short-scale and long-scale conventions assign it different values, the intended system of numeration should be clear from context. It is rarely used in ordinary everyday speech.
Easily confused with octillion
In the short scale, a septillion is 10^24 and an octillion is 10^27; in the long scale, they are respectively 10^42 and 10^48.