also: リテナー
noun
A device or appliance used to hold something in place, such as a dental retainer or a mechanical retaining component. The exact meaning depends on context.
矯正治療の後、歯並びを保つためにリテーナーを使います。
After orthodontic treatment, I use a retainer to keep my teeth in place.
この機械のリテーナーが外れているので、修理が必
The retainer on this machine has come off, so it needs repair.