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

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

They’re confident they will make it, with a swath of supporters from across the political spectrum and more than 105,000 signatures from all 88 Ohio counties collected in just three months since the campaign launch.

From Salon ● Jul. 9, 2026

“Everyone thinks of pawn as the lowest end of the credit spectrum, but I think they are sort of capitalizing on the K-shaped economy,” said Stephens’s Joseph.

From The Wall Street Journal ● Jul. 6, 2026

In their framework, information is stored through a spectrum of "quasi-normal modes" associated with the remnant's structure.

From Science Daily ● Jul. 5, 2026

When an intense beam of ordinary white light passes through a narrow slit and then through a prism or grating, it is spread into a rainbow of colors called a spectrum.

From "Cosmos" by Carl Sagan

In its current phase, the project uses robotic instruments to collect spectra from millions of objects across the sky, helping scientists study how stars, black holes, and galaxies evolve over time.

From Science Daily ● Apr. 4, 2026

Researchers have collected more than 600 million spectra from a region of sky spanning an area equivalent to more than 2,000 full Moons.

From Science Daily ● Mar. 8, 2026

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

Crucially, the simulated light spectra closely matched what astronomers observe from real systems.

From Science Daily ● Dec. 22, 2025

Humason and Hubble found, to their amazement, that the spectra of all the distant galaxies are red-shifted and, still more startling, that the more distant the galaxy was, the more red-shifted were its spectral lines.

From "Cosmos" by Carl Sagan

Most importantly, politicians across all spectrums of the party need to be much better listeners.

From Salon ● Feb. 21, 2026

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

“I’m questioning whether it is. … The Pride flag represents making space for all humans on all the spectrums, and this is where we’re going as a human species,” Cain said.

From Seattle Times ● Jun. 14, 2023

While the other mothers forced my sisters to trace their cursive letters, I worked on shades and spectrums.

From "The Belles" by Dhonielle Clayton

Related Words

• continuum
• range
• sphere