blueshift

US: (blo̅o̅′shift′)

WordReference Random House Unabridged Dictionary of American English © 2026

blue•shift  (blo̅o̅′shift′), n. [Astron.]

1. Astronomy a shift toward shorter wavelengths of the spectral lines of a celestial object, caused by the motion of the object toward the observer.

Also, blue′ shift′. 

• blue + shift 1950–55

Collins Concise English Dictionary © HarperCollins Publishers::

blueshift / ˈbluːˌʃɪft/ noun

1. a shift in the spectral lines of a stellar spectrum towards the blue end of the visible region relative to the wavelengths of these lines in the terrestrial spectrum: a result of the Doppler effect caused by stars approaching the solar system
   Compare redshift