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septillion

/sɛpˈtɪljən/

A thousand raised to the eighth power

From French sept- (seven).

noun
adjective
sept-
French
Verified
sept-
Prefix meaning “seven” in the naming system for large numbers

from French septillion

French
Verified
septillion
First recorded compound form; literally built with sept- plus -illion

from French septillion

-illion
French
Verified
-illion
Numerical word-forming suffix abstracted from million

from French septillion

French
AI-inferred
million
Model for the family of large-number names ending in -illion
Combined
French septillion
sept- combines with -illion to form the name of a large number
English, 1680s
Verified
septillion
Used in France and the United States for 10²⁴; in the traditional British long scale, 10⁴²

from French septillion

Modern English
septillion

A septillion sounds as though it ought to be a very grand “seven,” and in a sense it is: French sept- means “seven,” attached to the numerical suffix borrowed from million. The name was circulating by the 1680s, when mathematicians were turning huge quantities into pronounceable packages instead of forcing readers through endless columns of zeroes. In modern American and British short-scale usage, a septillion is 1 followed by 24 zeroes—the cube-sized mountain of digits represented as 10²⁴. Older British long-scale notation takes the same name much further, to 1 followed by 42 zeroes, a reminder that number names once crossed national borders with no passport agreement. And beware a false friend: the separate word sept, meaning a clan or enclosed group, has a tangled history involving sect and Latin saeptum; it is not the family tree behind the “seven” in septillion. Tomorrow’s memory hook is simple: septillion is the “seven-step” member of the -illion parade, standing at 10²⁴ in the short scale.

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