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

These hyperbolic fantasies of socialist surrealism are often exhilarating, but Riley’s wild spectrum of images and ideas doesn’t fit readily into a clear critique. —Richard Brody, New Yorker, 22 May 2026

The two cities represent opposite ends of the zero proof spectrum. —Lauren Schuster, Kansas City Star, 22 May 2026

Clinical Recovery Centers with Holistic Programs Some recovery retreats sit closer to the clinical end of the spectrum, pairing structured medical and therapeutic care with holistic wellness for guests dealing with chronic illness, addiction or co-occurring conditions. —Hanna Wickes, Sacbee.com, 20 May 2026

The researchers envision its flexible architecture being adapted for a wide spectrum of 3D imaging applications, ranging from tracking microscopic blood vessels during delicate surgeries to digitally mapping entire rooms and buildings. —Mrigakshi Dixit, Interesting Engineering, 20 May 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