| 1. | a person or thing that retains. |
| 2. | a servant or attendant who has served a family for many years. |
| 3. | Also called cage, separator. Machinery. a ring separating, and moving with, balls or rollers in a bearing. |
| 4. | Orthodontics.
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retainer re·tain·er (rĭ-tā'nər)
n.
One that retains, as a device, frame, or groove that restrains or guides, especially for a prosthesis.
An appliance used to hold teeth in position after orthodontic treatment.