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

see also:

on the spectrum

Synonyms of spectrum

• 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

Arday’s story has dominated headlines, with coverage spanning the political spectrum - and leaders from Prime Minister Andy Burnham down pressed for their opinions. — Rupert Neate, CNN Money, 16 Aug. 2026

But in between those ends of the roster spectrum, there was a lot to learn in the Pats’ preseason opener, especially with rookies Caleb Lomu, Gabe Jacas and Eli Raridon making their NFL exhibition debuts. — Andrew Callahan, Boston Herald, 15 Aug. 2026

This image, captured in the visible light spectrum, shows the solar corona similarly to how a human eye would see it during an eclipse through a green filter. — Jamie Carter, Forbes.com, 15 Aug. 2026

By combining observations of IRS 3's spectrum with simulations of how its light travels through different models of the surrounding material, researchers reconstructed the structure of the star's envelope. — Samantha Mathewson, Space.com, 14 Aug. 2026

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
• on the 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