<p><strong>Noun</strong></p><ul><li>a person or thing that retains</li><li>a servant or attendant who has served a family for many years</li><li>machinery: a ring separating, and moving with, balls or rollers in a bearing</li><li>orthodontics: a fixed or removable device worn in the mouth to hold the teeth in their new position during the adaptive period after straightening appliances have been removed</li><li>prosthodontics: a part on a bridge or the like by which the bridge is attached to the natural teeth</li></ul>