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

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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

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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

SpaceX is working to secure access to cell towers just weeks after buying more wireless spectrum.

From Barron's ● Oct. 23, 2026

Traditional spectrometers generally separate incoming light into its component wavelengths or use complex calculations to reconstruct its spectrum.

From Science Daily ● Oct. 23, 2026

Leaders from across the political spectrum have paid tribute to Haines, who was first elected in 2019 and is well regarded by her peers.

From BBC ● Oct. 21, 2026

The Elon Musk-led company made its biggest move yet into the wireless market last month, signing an $8 billion deal to buy cellular spectrum licenses from investment firm Grain Management.

From The Wall Street Journal ● Oct. 21, 2026

One puzzle that had been around for a long time had to do with spectrum readings of the wavelengths of hydrogen.

From "A Short History of Nearly Everything" by Bill Bryson

"The key insight was to go back to the mathematics and ask whether there was a fundamentally cleaner way to retrieve spectra," said Dr. Chunhui Yao, a lead author of the study.

From Science Daily ● Oct. 23, 2026

Webb and Spitzer revealed these features through mid-infrared spectra.

From Science Daily ● Oct. 7, 2026

Scientists expect to release images and spectra from some of Juice's instruments in the coming weeks, once the data have reached Earth and instrument teams have had time to evaluate them.

From Science Daily ● Oct. 3, 2026

Nearly 30 hours of exposure time collected enough light for the team to identify extremely faint absorption features in the spectra of the distant galaxies.

From Science Daily ● Oct. 2, 2026

In the years following his proof of the existence of other galaxies, Hubble spent his time cataloging their distances and observing their spectra.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

Among the contenders in this year’s original song race are two on opposite ends of multiple spectrums.

From Los Angeles Times ● Nov. 20, 2024

It's clear that coming out is still a complicated process despite Gen Z's more widespread understanding and acceptance of the gender and sexuality spectrums.

From Salon ● Aug. 15, 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

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Related Words

• continuum
• range
• sphere

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