Changes

==Origin==

==Origin==

New Latin, from [[Latin]], [[appearance]] — more at specter

New Latin, from [[Latin]], [[appearance]] — more at specter

In [[Latin]] ''spectrum'' means "image" or "[[apparition]]", including the [[meaning]] "[[spectre]]". Spectral [[evidence]] is [[testimony]] about what was done by spectres of persons not present physically, or hearsay evidence about what [[ghosts]] or apparitions of [[Satan]] said. It was used to convict a number of persons of witchcraft at Salem, Massachusetts in the late 17th century. The word "spectrum" [Spektrum] was strictly used to designate a ghostly optical afterimage by [http://en.wikipedia.org/wiki/Goethe Goethe] in his ''[http://en.wikipedia.org/wiki/Theory_of_Colours_(book) Theory of Colors]'' and [http://en.wikipedia.org/wiki/Arthur_Schopenhauer Schopenhauer] in ''[http://en.wikipedia.org/wiki/On_Vision_and_Colors On Vision and Colors]''.

In [[Latin]] ''spectrum'' means "image" or "[[apparition]]", including the [[meaning]] "[[spectre]]". Spectral [[evidence]] is [[testimony]] about what was done by spectres of persons not present physically, or hearsay evidence about what [[ghosts]] or apparitions of [[Satan]] said. It was used to convict a number of persons of witchcraft at Salem, Massachusetts in the late 17th century. The word "spectrum" [Spektrum] was strictly used to designate a ghostly optical afterimage by [https://en.wikipedia.org/wiki/Goethe Goethe] in his ''[https://en.wikipedia.org/wiki/Theory_of_Colours_(book) Theory of Colors]'' and [https://en.wikipedia.org/wiki/Arthur_Schopenhauer Schopenhauer] in ''[https://en.wikipedia.org/wiki/On_Vision_and_Colors On Vision and Colors]''.

*[http://en.wikipedia.org/wiki/17th_century 1671]

*[https://en.wikipedia.org/wiki/17th_century 1671]

==Definitions==

==Definitions==

*1a :  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

*1a :  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

:c :  a range of effectiveness against pathogenic organisms <an antibiotic with a broad spectrum>  

:c :  a range of effectiveness against pathogenic organisms <an antibiotic with a broad spectrum>  

==Description==

==Description==

A '''spectrum''' (plural spectra or spectrums) is a condition that is not limited to a specific set of [[values]] but can vary infinitely within a [[continuum]]. The word was first used scientifically within the field of [[optics]] to describe the [[rainbow]] of [[colors]] in visible light when separated using a prism. As scientific understanding of light advanced, it came to apply to the entire [http://en.wikipedia.org/wiki/Electromagnetic_spectrum electromagnetic spectrum].

A '''spectrum''' (plural spectra or spectrums) is a condition that is not limited to a specific set of [[values]] but can vary infinitely within a [[continuum]]. The word was first used scientifically within the field of [[optics]] to describe the [[rainbow]] of [[colors]] in visible light when separated using a prism. As scientific understanding of light advanced, it came to apply to the entire [https://en.wikipedia.org/wiki/Electromagnetic_spectrum electromagnetic spectrum].

Spectrum has since been applied by [[analogy]] to topics outside of optics. Thus, one might talk about the spectrum of political [[opinion]], or the spectrum of activity of a [[drug]], or the [[autism]] spectrum. In these uses, values within a spectrum may not be associated with precisely quantifiable numbers or [[definitions]]. Such uses imply a broad range of conditions or [[behaviors]] grouped together and studied under a single title for ease of [[discussion]].

Spectrum has since been applied by [[analogy]] to topics outside of optics. Thus, one might talk about the spectrum of political [[opinion]], or the spectrum of activity of a [[drug]], or the [[autism]] spectrum. In these uses, values within a spectrum may not be associated with precisely quantifiable numbers or [[definitions]]. Such uses imply a broad range of conditions or [[behaviors]] grouped together and studied under a single title for ease of [[discussion]].