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

Inflected Forms

noun

• 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

House, candidates across the spectrum are demonstrating just how deeply RCV has become woven into the state’s politics.

From Salon • Jun. 9, 2026

Keeping prices low at a time when most consumers up and down the income spectrum are focused on value makes sense, although it’s nothing new for Costco.

From Barron's • Jun. 8, 2026

It is broadly acknowledged now, across the political spectrum, that girls were terribly let down, in part because the authorities were worried about stirring up community tensions.

From BBC • Jun. 6, 2026

“By bringing together experts from across the political spectrum, we can remove partisan politics from the conversation and focus on practical, responsible solutions,” Bilirakis said.

From MarketWatch • Jun. 5, 2026

Moreover, radio represents a large fraction of the electromagnetic spectrum.

From "Cosmos" by Carl Sagan

Related Words

• continuum
• range
• sphere