What does ultraviolet mean?
Ultraviolet, often shortened to UV, refers to electromagnetic radiation with wavelengths shorter than violet light. It occupies the region of the spectrum immediately beyond violet, so it is not itself a visible color; instead, ultraviolet can be detected only through specialized instruments or through its effects on other substances and organisms. The term is used in astronomy, medicine, chemistry, biology, photography, and conservation, among many other fields. As an adjective, ultraviolet commonly modifies radiation, light, rays, wavelengths, filters, lamps, and spectrometers. The noun is generally uncountable when it means the radiation as a whole, while plural forms are uncommon. Ultraviolet carries both practical and cautionary associations: it is essential to certain laboratory procedures and helps reveal otherwise hidden features, but prolonged exposure can harm skin and eyes. Its name reflects its position beyond violet, the shortest-wavelength color that human vision can ordinarily perceive.
Electromagnetic radiation with wavelengths shorter than violet light, lying beyond the violet end of the visible spectrum.
"The instrument measured how much ultraviolet reached the surface."
Usually uncountable when referring to the radiation generally.
Denoting electromagnetic radiation with wavelengths shorter than violet light, or equipment that emits, detects, or is associated with such radiation.
"The technician checked the ultraviolet lamp before beginning the experiment."
Commonly used attributively, especially with light, radiation, rays, filters, and spectrometers.
Rare; the noun is usually uncountable when referring to ultraviolet radiation generally.
"The astronomers compared the ultraviolet detected at two different wavelengths."
Ultraviolet is named for its place in the spectrum: it lies just beyond violet, where the light becomes invisible to human eyes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ultraviolet come from?
The English compound was formed from Latin ultra, meaning “beyond,” and violet, the name of the visible color at the opposite end of the spectrum from red. Violet entered English through Old French and ultimately derives from Latin viola, while ultra is a Latin word meaning “beyond.” The combination describes radiation lying beyond the violet region; related English forms such as ultravioletce reflect the same Latin prefix ultra.
How ultraviolet is actually used
Ultraviolet is formal and scientific, though UV is extremely common in technical and general usage. The noun is usually treated as uncountable when referring to the radiation generally; plural forms are uncommon and usually refer to distinct emissions or wavelengths.
Easily confused with ultraviolet
Infrared radiation lies beyond the red end of the visible spectrum, whereas ultraviolet radiation lies beyond the violet end.
Violet is a visible color at the short-wavelength end of the spectrum, while ultraviolet is the invisible radiation immediately beyond it.