spectrum

noun

spec·​trum ˈspek-trəm 

plural spectra ˈspek-trə  or spectrums

1

a

: a continuum of color formed when a beam of white light is dispersed (as by passage through a prism) so that its component wavelengths are arranged in order

b

: any of various continua that resemble a color spectrum in consisting of an ordered arrangement by a particular characteristic (such as frequency or energy): such as

(1)

: electromagnetic spectrum

(2)

: radio spectrum

(3)

: the range of frequencies of sound waves

(4)

: mass spectrum

c

: the representation (such as a plot) of a spectrum

2

a

: a continuous sequence or range

a wide spectrum of interests

opposite ends of the political spectrum

b

: kinds of organisms associated with a particular situation (such as an environment)

c

: a range of effectiveness against pathogenic organisms

an antibiotic with a broad spectrum

Phrases

on the spectrum

: exhibiting traits associated with autism spectrum disorder

… quiet areas and sensory bags with headphones … and other ways to help kids who are on the spectrum cope with unfamiliar, noisy surroundings.

—Rachel Molenda

… Stephanie Adams, cofounder of the Autism and Asperger's Society, said: "We started the society because we wanted to make a place where people on the spectrum can spend their time and not feel isolated. …"

—Kelsey Maxwell

Synonyms

• range
• scale
• gamut

Examples of spectrum in a Sentence

beautiful scarves in all the colors of the spectrum

the complete spectrum of opinions on this hotly debated subject

Recent Examples on the Web

How the Autism Theater Project was born The theater program showcases lives on and off the spectrum in an authentic way, helping crew members and actors work on productions. —Miami Herald, 12 July 2025

Since 2012, private equity sponsors have financed almost 3,000 energy enterprises across the spectrum, worth $617 billion. —Ken Silverstein, Forbes.com, 9 July 2025

At the opposite end of the spectrum is Utah, which had the lowest cancer rate nationwide, with just 358 cases per 100,000 residents—a figure 45 percent lower than Maine's. —Alice Gibbs, MSNBC Newsweek, 9 July 2025

But Musk seems to now face the possibility of backlash from both sides of the political spectrum. —Chris Isidore, CNN Money, 8 July 2025

Word History

Etymology

New Latin, from Latin, appearance — more at specter

First Known Use

1672, in the meaning defined at sense 1a

Phrases Containing spectrum

• a broad spectrum
• absorption spectrum
• autism spectrum disorder
• autistic spectrum disorder
• broad-spectrum
• electromagnetic spectrum
• mass spectrum
• radio spectrum

Rhymes for spectrum

• electrum

Kids Definition

spectrum

noun

spec·​trum ˈspek-trəm 

plural spectra -trə  or spectrums

1

a

: the group of different colors including red, orange, yellow, green, blue, indigo, and violet arranged in the order of their wavelengths and seen when white light passes through a prism and falls on a surface or when sunlight is scattered by water droplets to form a rainbow

b

: electromagnetic spectrum

2

: a continuous range or series

a wide spectrum of interests

Medical Definition

spectrum

noun

spec·​trum ˈspek-trəm 

plural spectra -trə  or spectrums

1

a

: a continuum of color formed when a beam of white light is dispersed (as by passage through a prism) so that its component wavelengths are arranged in order

b

: any of various continua that resemble a spectrum in consisting of an ordered arrangement by a particular characteristic (as frequency or energy): as

(1)

: electromagnetic spectrum

(2)

: mass spectrum

c

: the representation (as a plot) of a spectrum

2

: a continuous sequence or range

specifically : a range of effectiveness against pathogenic organisms see broad-spectrum, narrow-spectrum