A servant who has usually been with the same family for a long time: old retainer He lives with a faithful old retainer in three rooms of the enormous house. SMART Vocabulary: related words and phrases. People who serve other people.
Traditional (Hawley) retainers have a piece of wire attached to plastic (or acrylic). Clear retainers (Essix) are also plastic but don't have any wires. Both are custom-made to fit your teeth.