regulus

n.; pl. E. Reguluses (-&unr_;z), L. Reguli [ L., a petty king, prince, dim. of rex, regis, a king: cf. F. régule. See Regal. ] 1. A petty king; a ruler of little power or consequence. [ 1913 Webster ]

2. (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. [ 1913 Webster ]

☞ The name was introduced by the alchemists, and applied by them in the first instance to antimony. It signifies little king; and from the facility with which antimony alloyed with gold, these empirical philosophers had great hopes that this metal, antimony, would lead them to the discovery of the philosopher's stone. Ure. [ 1913 Webster ]

3. (Astron.) A star of the first magnitude in the constellation Leo; -- called also the Lion's Heart. [ 1913 Webster ]