-illion

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.

-illion

1. Combined with Latin prefixes for names of integers in order to form names of powers of a million or of a thousand greater than 1,000,000. Thus we have the names billion, trillion, etc.
2. Added to various nonsense syllables to indicate an arbitrarily very large number.

• The words formed by combining the Latin prefix for the name of an integer ${\displaystyle n}$ (${\displaystyle n>1}$) with this suffix may mean ${\displaystyle 1,000,000^{n}}$ or ${\displaystyle 1000^{n+1}}$ depending on national practices. Hence billion can mean “million million” or “thousand million”. See the usage notes at Wiktionary’s appendix on numbers for more information.

• -illiard

• Indefinite and fictitious numbers on Wikipedia.Wikipedia

Back-formation from million, 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.

• IPA^(key): /i.ljɔ̃/

-illion m (plural -illions)

1. -illion

• -illiard