Etymologically
Log in

spectral

This is the current revision of this entry, as edited by bogdan on 31 October 2026 at 15:26. This address is a permanent link to this version.
Changes in this edit History

Pronunciation

  • /ˈspɛktɹəɫ/[1]

Etymology

In the senses relating to ghosts it is formed from English spectre + -al, and in those relating to the spectrum from English spectrum + -al.[2][3][4] The OED instead derives it from a presumed Latin *spectrālis, from spectrum, and compares French spectral.[5] The noun spectre is from spectre (“image, figure, ghost”), and spectrum from Latin spectrum (“appearance, image, apparition”),[2][6] from speciō (“to look at”), from Proto-Indo-European *spek- (“to observe”).[2][6]

Earliest recorded meaning

Able to see spectres: 1718, in F. Hutchinson's Historical Essay concerning Witchcraft, a sense now obsolete.[5][4][2] The OED also records an obsolete noun spectral, an apparition, in 1658.[5]

Semantic evolution

After its first use, of people able to see ghosts, the word came to mean "ghostly, unreal" in the Romantic period: in Shelley's Alastor (1816) in the OED,[5] from 1815 in Etymonline,[2] though Merriam-Webster dates this sense to 1769.[7] It then described things that look like or befit a ghost (Byron in 1821, Bulwer-Lytton in 1828).[5] With the science of the spectrum it took a second, technical meaning, "of the spectrum", from 1832,[5][2] later extended to analysis by means of the spectrum (1879) and, in mathematics, to the spectrum of a transformation (1948).[5] Etymonline notes the older spectrous, "ghostly", from the 1650s, later revived by Blake and Swinburne.[2]

Timeline

  • 1658 – noun, an apparition (obsolete).[5]
  • 1718 – able to see spectres (obsolete).[5][2]
  • 1769 – ghostly, in Merriam-Webster.[7]
  • 1815 – ghostly, in Etymonline.[2]
  • 1816 – ghostly, unsubstantial, in Shelley.[5]
  • 1821 – characteristic of a spectre.[5]
  • 1832 – of or relating to the spectrum.[5][2]
  • 1839 – produced only by the action of light on the eye.[5]
  • 1879 – carried out by means of the spectrum.[5]
  • 1948 – mathematics, of the spectrum of a transformation.[5]

Meanings

Adjective

  1. Of or like a ghost; ghostly: A spectral figure stood at the end of the corridor.[8][7][5]
  2. Lacking real substance; illusory.[7][5]
  3. Of, relating to or produced by a spectrum: spectral analysis.[8][7][5]
  4. (physics) Of a quantity, relating to a single wavelength of radiation.[8]
  5. (mathematics) Relating to the spectrum of a transformation or operator.[5]
  6. (obsolete, 1718) Able to see spectres.[5][4]

Word family

  • spectrality
  • spectrally
  • nonspectral
  • multispectral
  • spectral line
  • spectral type

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  3. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  4. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  5. ^ a b c d e f g h i j k l m n o p q r s t Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  6. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  7. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  8. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins