-illion

Meanings

1. Combined with Latin prefixes for names of integers in order to form names of powers of a million.
2. Added to various nonsense syllables to indicate an arbitrarily very large number.

Etymology

Back-formation from million, then used in billion, trillion, quadrillion, each from French, ultimately from Italian mille (“thousand”) and the augmentative suffix -one. -illion was segmented from million as if mi- was a prefix, and -illion the stem.