French word rajeunissement comes from French rajeunir

Detailed word origin of rajeunissement

Dictionary entry	Language	Definition
rajeunir	French (fra)	(figuratively, transitive) to bring back; to send back (remind of a past time). (figuratively, transitive) to take off (years from someone's age) (to make appear younger). (intransitive) to get younger. (transitive) to make young. (transitive) to rejuvenate.
rajeunissement	French (fra)	Getting younger. Making younger. Rejuvenation.