1 a sum of money that is paid to sb to make sure they will be available to do work when they are needed:
The agency will pay you a monthly retainer.
2 (BrE) a small amount of rent that you pay for a room, etc. when you are not there in order to keep it available for your use:
Check whether full rent or a retainer is required during vacations.
3 (AmE) a device that keeps a person's teeth straight after they have had ORTHODONTIC treatment with a BRACE
4 (old-fashioned) a servant, especially one who has been with a family for a long time
