Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The entire range over which some measurable property of a physical system or phenomenon can vary, such as the frequency of sound, the wavelength of electromagnetic radiation, or the mass of specific kinds of particles.
  • noun A graphic or photographic representation of such a measurable range; a spectrogram.
  • noun A range of radio frequencies assigned by a regulatory agency for use by a given group or organization.
  • noun A range of values of a quantity or set of related quantities.
  • noun A broad sequence or range of related qualities, ideas, or activities.

from The Century Dictionary.

  • noun A specter; a ghostly phantom.
  • noun An image of something seen, continuing after the eyes are closed, covered, or turned away.
  • noun In physics, the continuous band of light (visible spectrum) showing the successive prismatic colors, or the isolated lines or bands of color, observed when the radiation from such a source as the sun, or an ignited vapor in a gas-flame, is viewed after having been passed through a prism (prismatic spectrum) or reflected from a diffraction-grating (diffraction- or interference-spectrum).
  • noun In zoology, a generic name variously used:
  • noun A genus of lepidopterous insects.
  • noun A genus of gressorial orthopterous insects: same as
  • noun A genus of lemuroid mammals: same as
  • noun The specific name of some animals, including Tarsius spectrum and Phyllostoma spectrum.
  • noun That portion, of any spectrum, which consists of rays less refrangible than the longest wave-lengths of the visible spectrum.

from the GNU version of the Collaborative International Dictionary of English.

  • noun obsolete An apparition; a specter.
  • noun The several colored and other rays of which light is composed, separated by the refraction of a prism or other means, and observed or studied either as spread out on a screen, by direct vision, by photography, or otherwise. See Illust. of Light, and Spectroscope.
  • noun A luminous appearance, or an image seen after the eye has been exposed to an intense light or a strongly illuminated object. When the object is colored, the image appears of the complementary color, as a green image seen after viewing a red wafer lying on white paper. Called also ocular spectrum.
  • noun the spectrum of light which has passed through a medium capable of absorbing a portion of the rays. It is characterized by dark spaces, bands, or lines.
  • noun a spectrum of rays considered solely with reference to their chemical effects, as in photography. These, in the usual photogrophic methods, have their maximum influence at and beyond the violet rays, but are not limited to this region.
  • noun the visible colored rays of the solar spectrum, exhibiting the seven principal colors in their order, and covering the central and larger portion of the space of the whole spectrum.
  • noun a spectrum not broken by bands or lines, but having the colors shaded into each other continously, as that from an incandescent solid or liquid, or a gas under high pressure.
  • noun a spectrum produced by diffraction, as by a grating.
  • noun the spectrum of an incandesoent gas or vapor, under moderate, or especially under very low, pressure. It is characterized by bright bands or lines.
  • noun a representation of a spectrum arranged upon conventional plan adopted as standard, especially a spectrum in which the colors are spaced proportionally to their wave lengths, as when formed by a diffraction grating.
  • noun See Spectrum, 2 (b), above.
  • noun a spectrum produced by means of a prism.
  • noun the spectrum of solar light, especially as thrown upon a screen in a darkened room. It is characterized by numerous dark lines called Fraunhofer lines.
  • noun chemical analysis effected by comparison of the different relative positions and qualities of the fixed lines of spectra produced by flames in which different substances are burned or evaporated, each substance having its own characteristic system of lines.
  • noun a spectrum of rays considered solely with reference to their heating effect, especially of those rays which produce no luminous phenomena.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.
  • noun chemistry The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).
  • noun mathematics, linear algebra The set of eigenvalues of a matrix.
  • noun 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun an ordered array of the components of an emission or wave
  • noun a broad range of related objects or values or qualities or ideas or activities

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[Latin, appearance, from specere, to look at; see spek- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

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

Examples

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