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The visible spectrum
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From Latin spectrum (appearance, image, apparition), from speciō (look at, view). (see scope)



spectrum (plural spectra or spectrums)

  1. (obsolete) Specter, apparition. [from early 17th c.]
  2. 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[1]:
      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.
  3. 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.
  4. (psychology, education) The autism spectrum.
  5. (chemistry) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).
  6. (mathematics, linear algebra) The set of eigenvalues of a matrix.
  7. (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.
  8. (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.

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The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Wiktionary:Entry layout#Translations.




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



spectrum n (genitive spectrī); second declension

  1. appearance, image
  2. apparition, specter


Second declension.

Case Singular Plural
nominative spectrum spectra
genitive spectrī spectrōrum
dative spectrō spectrīs
accusative spectrum spectra
ablative spectrō spectrīs
vocative spectrum spectra

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