Cepheid

American  

[see-fee-id, sef-ee-id] / ˈsi fi ɪd, ˈsɛf i ɪd /

noun

plural

Cepheids

1. Astronomy. Cepheid variable.

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Cepheid Scientific  

/ sē′fē-ĭd,sĕf′ē- /

1. Any of a class of variable stars whose luminosity fluctuates with an extremely regular period. There is a strong correlation between the absolute magnitude of a Cepheid's luminosity and its period. By comparing the apparent magnitude of a Cepheid to the absolute magnitude corresponding to its period, it is possible to determine fairly accurately how distant the Cepheid is from Earth.

2. Also called Cepheid variable

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Example Sentences

These include Cepheid variable stars, which brighten and dim in predictable ways, red giant stars with known brightness, Type Ia supernovae, and certain galaxy types.

From Science Daily • Apr. 12, 2026

After the deal closes, Masimo is expected to operate as a stand-alone company within Danaher’s Diagnostics segment, alongside other businesses Radiometer, Leica Biosystems, Cepheid and Beckman Coulter Diagnostics, the people familiar with the matter said.

From The Wall Street Journal • Feb. 17, 2026

The Washington, D.C.–based conglomerate makes medical and scientific tools, spanning research to diagnostics, including Covid tests by its Cepheid division—one of the first-approved and widely used versions.

From Barron's • Jan. 8, 2026

She was particularly interested in Cepheid variables, which are stars whose brightness pulses regularly, so they get brighter and dimmer with a particular period.

From Salon • Feb. 14, 2025

A special type of star, called a Cepheid variable, had a property that allowed Hubble to measure the distance to faraway objects.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife