Noun
cepheid variable (plural cepheid variables)
(astronomy) A radially pulsating (expanding and contracting) variable star with a regular period and known relationship between period and intrinsic brightness.
Polaris, the brightest star in the constellation, is a yellow-white supergiant and the brightest Cepheid variable star in the night sky, ranging from an apparent magnitude of 1.97 to 2.00. Source: Internet
Comparisons of nova-based distance estimates to various nearby galaxies and galaxy clusters with those done with Cepheid variable stars have shown them to be of comparable accuracy. Source: Internet