reg·​u·​lus | \ ˈre-gyə-ləs \

Definition of regulus

 (Entry 1 of 2)

1 capitalized : a first-magnitude star in the constellation Leo
2 [ Medieval Latin, metallic antimony, from Latin ] : the more or less impure mass of metal formed beneath the slag in smelting and reducing ores


biographical name
Reg·​u·​lus | \ ˈre-gyə-ləs \

Definition of Regulus (Entry 2 of 2)

Marcus Atilius died circa 250 b.c. Roman general

Examples of regulus in a Sentence

Recent Examples on the Web: Noun

Regulus will be only three degrees away from the moon, about equal to the width of your two middle fingers held at arm’s length. National Geographic, "This Week’s Night Sky: See Jupiter as a NASA Probe Closes In," 4 July 2016

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'regulus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of regulus


1559, in the meaning defined at sense 1

History and Etymology for regulus


New Latin, from Latin, petty king, from reg-, rex king — more at royal

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The first known use of regulus was in 1559

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to settle judicially or to act as judge

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