Discontinuous spectrum
From The Glossary of Digital Photography
A spectrum of light that is not continuous, such as that produced by various types of lamps. Since various frequencies or wavelengths are missing, these kinds of sources tend to alter color when subjects are photographed. Vapor lights, such as sodium vapor lights, fluorescent lights, and arc lamps, have discontinuous spectrums. Using discontinuous spectrum lighting can make it difficult to get true color fidelity in images.
