magnitude

American  

[mag-ni-tood, -tyood] / ˈmæg nɪˌtud, -ˌtyud /

noun

1. size; extent; dimensions.

   to determine the magnitude of an angle.

2. great importance or consequence.

   affairs of magnitude.

3. greatness of size or amount.

4. moral greatness.

   magnitude of mind.

5. Astronomy.

   1. Also called apparent magnitude.  Also called visual magnitude,.  the brightness of a star or other celestial body as viewed by the unaided eye and expressed by a mathematical ratio of 2.512: a star of the first magnitude is approximately 2½ times as bright as one of the second magnitude and 100 times brighter than one of the sixth magnitude. Only stars of the sixth magnitude or brighter can be seen with the unaided eye.

   2. absolute magnitude.

6. Mathematics. a number characteristic of a quantity and forming a basis for comparison with similar quantities, as length.

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idioms

1. of the first magnitude, of utmost or major importance.

   an artist of the first magnitude.

magnitude British  

/ ˈmæɡnɪˌtjuːd /

noun

1. relative importance or significance

   a problem of the first magnitude

2. relative size or extent

   the magnitude of the explosion

3. maths a number assigned to a quantity, such as weight, and used as a basis of comparison for the measurement of similar quantities

4. Also called: apparent magnitude.  astronomy the apparent brightness of a celestial body expressed on a numerical scale on which bright stars have a low value. Values are measured by eye (visual magnitude) or more accurately by photometric or photographic methods, and range from –26.7 (the sun), through 1.5 (Sirius), down to about +30. Each integral value represents a brightness 2.512 times greater than the next highest integral value See also absolute magnitude visual magnitude

5. Also called: earthquake magnitude.  geology a measure of the size of an earthquake based on the quantity of energy released: specified on the Richter scale See Richter scale

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magnitude Scientific  

/ măg′nĭ-to̅o̅d′ /

1. 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.

2. ◆ 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.

3. ◆ 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.

4. ◆ 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.

5. A measure of the total amount of energy released by an earthquake, as indicated on the Richter scale.

6. See more at Richter scale

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Other Word Forms

• magnitudinous
  adjective
• overmagnitude
  noun

Etymology

Origin of magnitude

First recorded in 1350–1400; Middle English word from Latin word magnitūdō. See magni-, -tude

Explanation

Earthquakes have great magnitude in that they are powerful. Their power is rated by their level of magnitude, or how much energy they release relative to other earthquakes. In math, magnitude compares numbers by powers of 10. If your weekly allowance was $10, but your brother's was $100, his allowance would be one order of magnitude higher than yours. If your sister's was $10,000, hers would be three orders of magnitude higher. A difference of that magnitude is just not fair!

Example Sentences

"Because the second component is not administered separately and systemically, but 'travels along' with the incretin part, it can be used at a dose that is orders of magnitude lower."

From Science Daily • May 7, 2026

But the magnitude of such longer-run responses “will be entirely determined by how long U.S. consumers must deal with higher prices at the pump,” he said.

From MarketWatch • May 5, 2026

That is not necessarily what it would cost to bring the infrastructure up to date, but it offers a snapshot of the magnitude of the repairs local governments will need to address in coming years.

From The Wall Street Journal • May 5, 2026

“When many conservative assumptions are stacked on top of each other, the cumulative effect can produce an estimated ‘safe’ exposure level that is orders of magnitude below naturally occurring levels in the environment,” he wrote.

From Salon • May 5, 2026

But I guess it’s finally hitting me—the magnitude of this change.

From "Leah on the Offbeat" by Becky Albertalli

Related Words

• amount
• breadth
• capacity
• dimension
• enormity
• extent
• immensity
• intensity
• measurement
• proportion
• quantity
• strength
• volume