onlay [AS, ana, up, licagan, to lie] , 1. (in dentistry) a cast type of metal restoration retained by friction, dental luting cement, and mechanical forces in a prepared tooth, used for restoring one or more of the tooth’s cusps and adjoining occlusal surfaces. Compare inlay, def. 2. 2. (in dentistry) an occlusal rest part of a removable partial denture, extended to cover the entire occlusal surface of a tooth.
