regulus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The metallic mass that sinks to the bottom of a furnace or crucible during smelting.
• noun A relatively impure intermediate product of various ores in smelting.

from The Century Dictionary.

• noun In metallurgy: The metallic mass which sinks to the bottom of a furnace or crucible, separating itself from the slag by gravity.
• noun An intermediate product obtained in smelting ores, especially those of copper, lead, silver, and nickel, and consisting chiefly of metallic sulphids.
• noun One set of generators of a quadric surface; the system of straights that meet three non-incident straights.
• noun A configuration of lines which satisfy three conditions, and therefore depend on only one parameter.
• noun In ornithology: An old name of the goldcrest or crested wren of Europe; a kinglet.
• noun The typical genus of Regulinæ; the kinglets.
• noun In alchemy and early chemistry, the reduced or metallic mass obtained in the treatment of various ores, particularly those of the semi-metals (see metal); especially, metallic antimony (regulus antimonii): but various alloys of antimony, other brittle metals, and even the more perfect metals were also occasionally so called, to indicate that they were in the metallic condition.
• noun A very white star, of magnitude 1.4, on the heart of the Lion; a Leonis.
• noun In geometry, a ruled surface or singly infinite system of straight lines, where consecutive lines do not intersect.

from the GNU version of the Collaborative International Dictionary of English.

• noun A petty king; a ruler of little power or consequence.
• noun (Chem. & Metal.) The button, globule, or mass of metal, in a more or less impure state, which forms in the bottom of the crucible in smelting and reduction of ores.
• noun (Astron.) A star of the first magnitude in the constellation Leo; -- called also the Lion's Heart.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun an impure metal formed beneath slag during the smelting of ores.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a genus of birds of the family Sylviidae including kinglets
• noun the brightest star in Leo