Magnitude definition

măgnĭ-to͝od, -tyo͝od
(astron.) A number representing the apparent brightness of a celestial body: originally a number in a scale of values 1-6 and applied only to objects (excluding the sun and moon) visible to the naked eye, with the brightest stars at c. 1.5 (1 is the first magnitude) and stars at c. 6 (sixth magnitude) being barely visible, the scale now includes the sun (at −26.7) and moon (c. −12.7 when full) as well as the faintest objects visible telescopically (c. 36): each increase of one magnitude represents an increase of 2.512 times the brightness.
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(geol.) A measure of the amount of energy released by an earthquake.
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Size or measurable quantity.

The magnitude of a velocity.

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A measure of the total amount of energy released by an earthquake, as indicated on the Richter scale.
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(seismology) A measure of the energy released by an earthquake (e.g. on the Richter scale).
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The brightness of a celestial body on a numerical scale for which brighter objects have smaller values. Differences in magnitude are based on a logarithmic scale that matches the response of the human eye to differences in brightness so that a decrease of one magnitude represents an increase in apparent brightness by a factor of 2.512.
noun
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A property that can be described by a real number, such as the volume of a sphere or the length of a vector.
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(math.) A number given to a quantity for purposes of comparison with other quantities of the same class.
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A unit on such a scale of brightness.
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A number assigned to a quantity so that it may be compared with other quantities.
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Loudness (of sound)
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Importance or influence.
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(uncountable, countable) The absolute or relative size, extent or importance of something.
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(countable) An order of magnitude.
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(mathematics) A number, assigned to something, such that it may be compared to others numerically.
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(mathematics) Of a vector, the norm, most commonly, the two-norm.
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(astronomy) The apparent brightness of a star (on a negative, logarithmic scale); apparent magnitude.
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Magnitude is defined as large in size or very important.

An example of magnitude is the depth of the Grand Canyon.

An example of magnitude is the size of the problem of world hunger.

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(geology) A measure of the amount of energy released by an earthquake, as indicated on the Richter scale.
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Greatness of rank or position.
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Greatness in size or extent.

The magnitude of the flood was impossible to comprehend.

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Greatness in significance or influence.

Was shocked by the magnitude of the crisis.

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The degree of brightness of a star or other celestial body, measured on a logarithmic scale in which lower numbers mean greater brightness, such that a decrease of one unit represents an increase in brightness by a factor of 2.512. An object that is 5 units less than another object on the magnitude scale is 100 times more luminous. Because of refinements in measurement after the zero point was assigned, very bright objects have negative magnitudes. &diamf3; The brightness of a celestial body as seen from Earth is called its apparent magnitude . (When unspecified, an object's magnitude is normally assumed to be its apparent magnitude.) The dimmest stars visible to the unaided eye have apparent magnitude 6, while the brightest star in the night sky, Sirius, has apparent magnitude −1.4. The full Moon and the Sun have apparent magnitudes of −12.7 and −26.8 respectively. &diamf3; The brightness of a celestial body computed as if viewed from a distance of 10 parsecs (32.6 light-years) is called its absolute magnitude . Absolute magnitude measures the intrinsic brightness of a celestial object rather than how bright it appears on Earth, using the same logarithmic scale as for apparent magnitude. Sirius has an absolute magnitude of 1.5, considerably dimmer than Rigel which, though its apparent magnitude is 0.12, has an absolute magnitude of −8.1. Stars that appear dim in the night sky but have bright absolute magnitudes are much farther from Earth than stars that shine brightly at night but have relatively dim absolute magnitudes. The Sun, a star of only medium brightness, has an absolute magnitude of 4.8. &diamf3; The degree of total radiation emitted by a celestial body, including all infrared and ultraviolet radiation in addition to visible light, is called its bolometric magnitude . Bolometric magnitude is generally measured by applying a standard correction to an object's absolute magnitude.
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Greatness.
  • Of size.
  • Of extent.
  • Of importance or influence.
  • (obs.) Of character.
noun
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of the first magnitude
  • of the greatest importance
idiom
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Other Word Forms

Noun

Singular:
magnitude
Plural:
magnitudes

Idioms and Phrasal Verbs

of the first magnitude

Origin of magnitude

  • Middle English from Old French size from Latin magnitūdō greatness, size from magnus great meg- in Indo-European roots

    From American Heritage Dictionary of the English Language, 5th Edition

  • From Latin magnitÅ«dō (“greatness, size"); magni- +"Ž -itude

    From Wiktionary