Mira

noun

Mi·ra ˈmī-rə

astronomy

: a variable binary star system that is seen in the constellation Cetus

To see a star that varies intrinsically in brightness, we have to wait until late summer and fall. Mira, in the constellation Cetus the Whale, is the sky's best slowly varying red giant. Mira climbs from invisibility (at 9th magnitude) to 4th magnitude and then fades again roughly every 330 days.—

Alister Ling, Astronomy, January 1992

called also Omicron Ceti

Note: The star that we see when look at Mira is a variable red giant, the brightest of a binary pair of variable stars, and was one of the first variable stars identified by astronomers.