mir·ror  a polished surface that reflects sufficient light to yield images of objects in front of it. concave mirror, one with a concave reflecting surface. convex mirror, one with a convex reflecting surface. dental mirror, mouth m. frontal mirror, head m. Glatzel mirror, a mirror held below the nose for receiving moist breath to assess nasal patency; see also pneumatype. head mirror, a circular mirror strapped to the head of the examiner to reflect light into a cavity, especially the nose, pharynx, or larynx. Called also frontal m. mouth mirror, a small mirror, magnifying or nonmagnifying, used to reflect the operating field in the oral cavity, to retract the tissues and tongue, and to protect the tissues from injury during operation. Called also dental m. See also dental reflector, under reflector. nasographic mirror, Glatzel m. plane mirror, one with a flat reflecting surface.