- the dividing of a spectral line or lines as a result of placing a radiation source in a magnetic field. The division consists of three equally spaced lines (normal Zeeman effect ) in systems for which the spin quantum number is zero, or of three or more unequally spaced lines (anomalous Zeeman effect ) in systems for which the spin quantum number is not zero.
- the splitting of a spectral line of a substance into several closely spaced lines when the substance is placed in a magnetic field
