/reg"yeuh leuhs/ , n. , pl. reguluses, reguli /-luy'/ .
1. ( cap. ) Astron. a first magnitude star in the constellation Leo.
2. Metall.
a. the metallic mass that forms beneath the slag at the bottom of the crucible or furnace in smelting ores.
b. an impure intermediate product obtained in smelting ores.
[ 1550-60; regulus lit., little king (dim. of rex ); in early chemistry, antimony, so called because it readily combines with gold (the king of metals); see -ULE ]