Illustrated Glossary of Organic Chemistry

Bathochromic shift: In spectroscopy, the position shift of a peak or signal to longer wavelength (lower energy). Also called a red shift. A hypsochromic shift is the shift of a peak or signal to shorter wavelength (higher energy). Also called a blue shift.

For an absorption peak starting at λ_max = 550 nm, a shift to higher wavelength such as 650 nm is bathochromic, whereas a shift to lower wavelength such as 450 nm is hypsochromic.