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• regulus
  regulus

  noun

  Regulus, a first magnitude star in the constellation Leo.
• Regulus
  Regulus

  noun

  Marcus Atilius died 250? b.c., Roman general.

regulus

¹ American  

[reg-yuh-luhs] / ˈrɛg jə ləs /

noun

• reguluses,
  plural
• reguli
  plural

1. Astronomy. Regulus, a first magnitude star in the constellation Leo.

2. Metallurgy.

   1. the metallic mass that forms beneath the slag at the bottom of the crucible or furnace in smelting ores.

   2. an impure intermediate product obtained in smelting ores.

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Regulus ² American  

[reg-yuh-luhs] / ˈrɛg jə ləs /

noun

1. Marcus Atilius died 250? b.c., Roman general.

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regulus ¹ British  

/ ˈrɛɡjʊləs /

noun

1. impure metal forming beneath the slag during the smelting of ores

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Regulus ² British  

/ ˈrɛɡjʊləs /

noun

1. the brightest star in the constellation Leo. Visual magnitude: 1.3; spectral type: B8; distance: 69 light years

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Regulus ³ British  

/ ˈrɛɡjʊləs /

noun

1. Marcus Atilius (ˈmɑːkəs əˈtɪlɪəs). died ?250 _bc , Roman general; consul (267; 256). Captured by the Carthaginians in the First Punic War, he was sent to Rome on parole to deliver the enemy's peace terms, advised the Senate to refuse them, and was tortured to death on his return to Carthage

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Regulus Scientific  

/ rĕg′yə-ləs /

1. A bright triple star in the constellation Leo, with an apparent magnitude of 1.35. Scientific name: Alpha Leonis.

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Other Word Forms

Derived Forms

• reguline
  adjective

Inflected Forms

Nouns

• reguli
  plural
• reguluses
  plural

Etymology

Origin of regulus

First recorded in 1550–60; from Latin rēgulus literally, “little king” (diminutive of rēx ); in early chemistry, “antimony,” so called because it readily combines with gold (the king of metals); see -ule

Example Sentences

See Examples For:

regulus Regulus reguli

Crude antimony, which has been much used in the experiments of alchemists, is a combination of sulphur and regulus of antimony.

From Heads of Lectures on a Course of Experimental Philosophy: Particularly Including Chemistry by Joseph Priestley

For clarity we introduced the term "regulus" for the Latin mistura.

From De Re Metallica, Translated from the First Latin Edition of 1556 by Georgius Agricola

As to the recovery of the silver from the regulus, he states that 66 librae of silver give 132 librae of regulus.

From De Re Metallica, Translated from the First Latin Edition of 1556 by Georgius Agricola

When gold is parted from sixty-six librae of silver, the silver, copper, and sulphur regulus weighs one hundred and thirty-two librae.

From De Re Metallica, Translated from the First Latin Edition of 1556 by Georgius Agricola

For example, silver in bullion and in ores; copper precipitates or regulus, and copper ores and slags; and "black tin" and tin ores.

From A Text-book of Assaying: For the Use of Those Connected with Mines. by Cornelius Beringer

Regulus aims this year to start work on a site to produce triple-base propellant, a particularly powerful variant that the U.S. hasn’t produced since 1986, Somerindyke said.

From The Wall Street Journal ● Jul. 28, 2026

Some standouts: Regulus Therapeutics went up 120%; 89bio went up 85%; Chimerix gained 69% and Intra-Cellular Therapies rose 57%.

From MarketWatch ● Nov. 3, 2025

Novartis AG agreed to buy US biotech Regulus Therapeutics Inc. in a deal that could be valued at up to $1.7 billion.

From Los Angeles Times ● May 2, 2025

Find the Plough and trace a line down from the two stars on the right until you find Regulus, the brightest star in the constellation of Leo.

From BBC ● Nov. 17, 2024

Sirius was the very last of the line as his younger brother, Regulus, predeceased him and both were childless.

From "Harry Potter and the Half-Blood Prince" by J.K. Rowling

Mr. Ray himself had no knowledge of this bird, but received his account from Mr. Johnson, who apparently confounds it with the reguli non cristati, from which it is very distinct.

From The Natural History of Selborne by Gilbert White

The Vulgate has it, "in caverna reguli;" which, however, is not classic Latin.

From The Grammar of English Grammars by Goold Brown

Mr. Ray himself had no knowledge of this bird, but received his account from Mr. Johnson, who apparently confounds it with the reguli non cristati, from which it is very distinct. 

From The Natural History of Selborne, Vol. 1 by Henry Morley

These ealdermen, or earls, were honoured with titles of reguli subreguli, principes, patricii, and some times rex.

From The Mirror of Literature, Amusement, and Instruction Volume 13, No. 357, February 21, 1829 by Various

In the middle of the ninth century, Harold Harfager, one of the reguli of Norway, subdued the other petty rulers, and made himself king of the whole country.

From Notes and Queries, Number 182, April 23, 1853 A Medium of Inter-communication for Literary Men, Artists, Antiquaries, Genealogists, etc. by George Bell