spectrum

American  

[spek-truhm] / ˈspɛk trəm /

noun

spectra, plural spectrums plural

1. Physics.

   1. an array of entities, as light waves or particles, ordered in accordance with the magnitudes of a common physical property, as wavelength or mass: often the band of colors produced when sunlight is passed through a prism, comprising red, orange, yellow, green, blue, indigo, and violet.

   2. this band or series of colors together with extensions at the ends that are not visible to the eye, but that can be studied by means of photography, heat effects, etc., and that are produced by the dispersion of radiant energy other than ordinary light rays.

2. a broad range of varied but related ideas or objects, the individual features of which tend to overlap so as to form a continuous series or sequence.

   the spectrum of political beliefs.

3. the range of traits and behaviors that are considered to be characteristic of autism spectrum disorder.

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idioms

1. on the spectrum, having an autism spectrum disorder, or displaying behaviors considered characteristic of those disorders.

   The nonprofit works to increase public awareness about the day-to-day issues faced by people on the spectrum.

spectrum British  

/ ˈspɛktrəm /

noun

1. the distribution of colours produced when white light is dispersed by a prism or diffraction grating. There is a continuous change in wavelength from red, the longest wavelength, to violet, the shortest. Seven colours are usually distinguished: violet, indigo, blue, green, yellow, orange, and red

2. the whole range of electromagnetic radiation with respect to its wavelength or frequency

3. any particular distribution of electromagnetic radiation often showing lines or bands characteristic of the substance emitting the radiation or absorbing it See also absorption spectrum emission spectrum

4. any similar distribution or record of the energies, velocities, masses, etc, of atoms, ions, electrons, etc

   a mass spectrum

5. any range or scale, as of capabilities, emotions, or moods

6. another name for an afterimage

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spectrum Scientific  

/ spĕk′trəm /

spectra plural

1. A range over which some measurable property of a physical phenomenon, such as the frequency of sound or electromagnetic radiation, or the mass of specific kinds of particles, can vary. For example, the spectrum of visible light is the range of electromagnetic radiation with frequencies between between 4.7 × 10 ¹⁴ and 7.5 × 10 ¹⁴ hertz.

2. The observed distribution of a phenomenon across a range of measurement.

3. See more at atomic spectrum spectroscopy

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spectrum Cultural  

1. The range of wavelengths characteristic of a specific type of radiation.

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Discover More

The spectrum making up visible light contains light in the colors violet, indigo, blue, green, yellow, orange, and red, with violet having the shortest wavelength and highest frequency, and red having the longest wavelength and lowest frequency.

Other Word Forms

Noun Inflected Forms

• spectra
  plural
• spectrums
  plural

Etymology

Origin of spectrum

First recorded in 1605–15; from Latin: “appearance, form,” equivalent to spec(ere) “to look at, regard” + -trum instrumental noun suffix

Explanation

A spectrum is a broad range of similar things or qualities, like the wide spectrum of political beliefs in this country, ranging anywhere from super conservative to über-liberal and everything in between. Our modern definition of spectrum started out in the 1600s, when scientists used it to refer to the band of colors formed by a beam of light, like a rainbow. In physics, it’s a word that describes the distribution of something, like energy or atomic particles. We still use those scientific meanings today, but spectrum can also apply to non-science related groupings or ranges of related things.

Example Sentences

See Examples For:

spectrum spectra spectrums

Progressives have long framed a spectrum of issues in economic terms, said Usamah Andrabi, spokesperson for the progressive caucus Justice Democrats.

From Los Angeles Times ● Jul. 17, 2026

A survey from the BPC earlier this year found that 89% of voters from across the political spectrum wanted action from Congress to make housing more affordable.

From BBC ● Jul. 11, 2026

Their central role in AI is increasingly worrisome to many across the political spectrum.

From The Wall Street Journal ● Jul. 11, 2026

A Dyson swarm, by contrast, would consist of radiator panels rather than dust, giving it an unusually "clean" spectrum.

From Science Daily ● Jul. 10, 2026

The truth was every single color in a rainbow spectrum, and Maya didn’t have the words to say what she felt.

From "Far from the Tree" by Robin Benway

Roughly 99% of those objects will be observed only photometrically, meaning through images taken in different colors rather than detailed spectra.

From Science Daily ● Jun. 29, 2026

A few days after the initial flash, it brightened again, shifted to bluer light, and showed hydrogen in its spectra.

From Science Daily ● Apr. 24, 2026

The team also compared the images with spectra from major facilities such as Gemini.

From Science Daily ● Dec. 31, 2025

Those spectra tracked changing signatures in the ejected gas, and new spectral features matched up with structures seen in the interferometric images, providing a direct one-to-one confirmation of how the flows were forming and colliding.

From Science Daily ● Dec. 31, 2025

Some scientists think that when expansion is followed by contraction, when the spectra of distant galaxies are all blue-shifted, causality will be inverted and effects will precede causes.

From "Cosmos" by Carl Sagan

Explain to me why they're important for us to get clarity on, within those spectrums.

From Salon ● Aug. 20, 2023

In the last 15 years or so, psychiatry has embraced what’s called a dimensional approach, based on the idea of scales and spectrums of trait and symptom severity.

From Scientific American ● Jul. 24, 2023

Like “Lioness,” both the “Avatar” movies and the Marvel films are also about war and the spectrums of “good” and “evil.”

From Los Angeles Times ● Jul. 18, 2023

“These surveys tend to include much broader spectrums of trans individuals, and we cannot be as certain that our results are as problematic in the broader group,” Dr. Frisch said.

From New York Times ● Jun. 27, 2023

We're just different, like we exist on different spectrums.

From "Starfish" by Akemi Dawn Bowman

Related Words

• continuum
• range
• sphere