Real Dictionary

redshift in American English
the shift of spectral lines toward the longer wavelengths and lower frequencies at the red end of the spectrum in a luminous celestial body, indicating that the light source is moving rapidly away from the observer: thought to be a Doppler effect explaini
noun: a shift toward longer wavelengths of the spectral lines emitted by a celestial object that is caused by the object moving away from the earth

redshift in British English
noun: a shift in the lines of the spectrum of an astronomical object towards a longer wavelength (the red end of an optical spectrum), relative to the wavelength of these lines in the terrestrial spectrum, usually as a result of the Doppler effect caused by the