Pronunciation: (spek'yu-lum),[key] —n., —pl.-laPronunciation: (-lu),[key]-lums. 1. a mirror or reflector, esp. one of polished metal, as on a reflecting telescope.
2. See speculum metal. 3. Surg.an instrument for rendering a part accessible to observation, as by enlarging an orifice.
4. Ornith.a lustrous or specially colored area on the wings of certain birds.