Regulus (n.)

bright star in constellation Leo, 1550s, Modern Latin, apparently first so-called by Copernicus, literally "little king," diminutive of rex "king" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule"). Probably a translation of Basiliskos "little king," a Hellenistic Greek name for the star, mentioned in Geminos and Ptolemy (in the "Almagest," though elsewhere in his writings it is usually "the star on the heart of Leo"); perhaps a translation of Lugal "king," said to have been the star's Babylonian name. Klein holds it to be a corruption of Arabic rijl (al-asad) "paw of the lion" (compare Rigel).