Something laid or applied over something else, as to add relief to a surface.
Medicine A graft applied to the surface of the recipient organ or structure.
Dentistry A cast, usually made of gold, attached to the occlusal surface of a tooth.
onlay on·lay (ŏn'lā') n.
A cast restoration, usually made of gold, that is attached to the occlusal surface of a tooth.
A bone graft applied to the exterior surface of the bone.