Spĕc'ŭ-lūm, n.
n.; pl. SPĔC'Ŭ-LA. [Lat., from specere, to look, behold; It. speglio, specchio, Pg. espelho, Pr. espelh, Sp. espejo, H. Ger. & D. spiegel, L. Ger. spegel, speigel, speil, Icel. spegill, Sw. spegel, Dan. speil.]
Sense 1. A mirror or looking-glass.
Sense 2. A reflector of polished metal, especially such as is used in reflecting telescopes, made of an alloy of copper and tin, or of a coating of silver deposited on a surface of glass.
Sense 3. (Surg.) An instrument for dilating certain passages of the body, and throwing the light within them, thus facilitating their examination, or surgical operations.
Sense 4. (Nat. Hist.) A bright spot, often iridescent, upon animals, as upon the tails of peacocks, the wings of ducks, and the like.
Speculum metal, an alloy used for making the reflectors of telescopes and other instruments, usually consisting of thirty-two parts of copper, and fifteen of tin, with sometimes a small proportion of arsenic added to improve the whiteness.