French word vingtaine comes from French vingt (Twenty Twenty.), French -aine

Detailed word origin of vingtaine

Dictionary entry	Language	Definition
vingt	French (fra)	Twenty Twenty.
-aine	French (fra)	(noun, or, adjective) (demonyms). (noun-only) Indicates approximation, suffixed to a number.
vingtaine	French (fra)	About twenty.

Words with the same origin as vingtaine