spectrum

From Latin spectrum (“appearance, image, apparition”), from speciō (“look at, view”). Doublet of specter. See also scope.

• (Canada, UK) IPA^(key): /ˈspektɹəm/
• (US) IPA^(key): /ˈspɛkt(ʃ)ɹəm/
• Rhymes: -ɛktɹəm

spectrum (plural spectra or spectrums)

1. A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.
   • 2012 November 7, Matt Bai, “Winning a Second Term, Obama Will Confront Familiar Headwinds”, in New York Times‎:

     As Mr. Obama prepared to take the oath, his approval rating touched a remarkable 70 percent in some polling — a reflection of good will across the political spectrum.

2. Specifically, a range of colours representing light (electromagnetic radiation) of contiguous frequencies; hence electromagnetic spectrum, visible spectrum, ultraviolet spectrum, etc. [from later 17th c.]
   • 2010 October 30, Jim Giles, Jammed!, in New Scientist,

     Current 3G technologies can send roughly 1 bit of data - a one or a zero - per second over each 1 Hz of spectrum that the operator owns.

3. (psychology, education) The autism spectrum.
4. (chemistry) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).
5. (mathematics, linear algebra) The set of eigenvalues of a matrix.
6. (mathematics, functional analysis) Of a bounded linear operator A, the set of scalar values λ such that the operator A—λI, where I denotes the identity operator, does not have a bounded inverse; intended as a generalisation of the linear algebra sense.
7. (abstract algebra, algebraic geometry) The set, denoted Spec(R), of all prime ideals of a given ring R, commonly augmented with a Zariski topology and considered as a topological space.
8. (obsolete) Specter, apparition. [from early 17th c.]
9. The image of something seen that persists after the eyes are closed.

• light spectrum
• spectro-
• spectrum disorder
• political spectrum

• spectral

• cepstrum, crumpets

From Latin spectrum (“appearance, image, apparition”), from speciō (“look at, view”).

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spectrum n (plural spectrums or spectra, diminutive spectrumpje n)

1. spectrum

• spectraal
• spectroscoop

From spec(iō) (“look at, behold”) +‎ -trum. Confer with speculum.

• (Classical) IPA^(key): /ˈspek.trum/, [ˈspɛk.trũ]

spectrum n (genitive spectrī); second declension

1. appearance, image
2. apparition, specter

Second declension.

• speciō
• spectiō
• spectō

• Catalan: espectre
• Dutch: spectrum
• English: spectre, specter; spectrum
• French: spectre
• German: Spektrum
• Irish: speictream
• Italian: spettro
• Portuguese: espectro
• Romanian: spectru
• Russian: спектр (spektr)
• Spanish: espectro
• Swedish: spektrum

• spectrum in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• spectrum in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• spectrum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition, 1883–1887)
• spectrum in Gaffiot, Félix (1934) Dictionnaire Illustré Latin-Français, Hachette