Definitions

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

  • n. Physics The distribution of a characteristic of a physical system or phenomenon, especially:
  • n. Physics The distribution of energy emitted by a radiant source, as by an incandescent body, arranged in order of wavelengths.
  • n. Physics The distribution of atomic or subatomic particles in a system, as in a magnetically resolved molecular beam, arranged in order of masses.
  • n. A graphic or photographic representation of such a distribution.
  • n. A range of values of a quantity or set of related quantities.
  • n. A broad sequence or range of related qualities, ideas, or activities: the whole spectrum of 20th-century thought.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.
  • n. The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).
  • n. The set of eigenvalues of a matrix.
  • n. 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 the GNU version of the Collaborative International Dictionary of English

  • n. An apparition; a specter.
  • n.
  • n. 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.
  • n. 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.

from The Century Dictionary and Cyclopedia

  • n. A specter; a ghostly phantom.
  • n. An image of something seen, continuing after the eyes are closed, covered, or turned away.
  • n. 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).
  • n. In zoology, a generic name variously used:
  • n. A genus of lepidopterous insects.
  • n. A genus of gressorial orthopterous insects: same as
  • n. A genus of lemuroid mammals: same as
  • n. The specific name of some animals, including Tarsius spectrum and Phyllostoma spectrum.
  • n. That portion, of any spectrum, which consists of rays less refrangible than the longest wave-lengths of the visible spectrum.

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

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

Etymologies

Latin, appearance, from specere, to look at; see spek- in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin spectrum ("appearance, image, apparition"), from speciō ("look at, view"). (see scope) (Wiktionary)

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