retainer

noun6

1. •
   Any thing or person that retains.
2. •
   A device that holds teeth in position after orthodontic treatment.

   • You give me head / It makes it worse / Take out your fuckin' retainer / Put it in your purse — 1981
3. •
   A retaining valve.
4. •
   A fee one pays to reserve the other's time for services.

   • This lawyer charges a retainer for his work.
5. •
   A dependent or follower of someone of rank.

   • If they possessed the means to marshal labour, pile up food resources and provender armies of year-round retainers, what sort of royalty would consciously elect not to do so. — 2021
6. •
   A paid servant, especially one who has been employed for many years.

   • Of all this family lore I knew but little and vaguely; only what is to be gathered from the fireside talk of old retainers in the nursery. — 1865