Bathochromic shift

In spectroscopy, bathochromic shift (from Greek βαθύς (bathys) 'deep', and χρῶμα (chrōma) 'color'; hence less common alternate spelling "bathychromic") is a change of spectral band position in the absorption, reflectance, transmittance, or emission spectrum of a molecule to a longer wavelength (lower frequency). Because the red color in the visible spectrum has a longer wavelength than most other colors, the effect is also commonly called a red shift.

Hypsochromic shift is a change to shorter wavelength (higher frequency).