magnitude

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Greatness of rank or position: "such duties as were expected of a landowner of his magnitude” ( Anthony Powell).
2. n. Greatness in size or extent: The magnitude of the flood was impossible to comprehend.
3. n. Greatness in significance or influence: was shocked by the magnitude of the crisis.
4. n. Astronomy The degree of brightness of a celestial body designated on a numerical scale, on which the brightest star has magnitude -1.4 and the faintest visible star has magnitude 6, with the scale rule such that a decrease of one unit represents an increase in apparent brightness by a factor of 2.512. Also called apparent magnitude.
5. n. Mathematics A number assigned to a quantity so that it may be compared with other quantities.
6. n. Mathematics A property that can be described by a real number, such as the volume of a sphere or the length of a vector.
7. n. Geology A measure of the amount of energy released by an earthquake, as indicated on the Richter Scale.

Century Dictionary and Cyclopedia

1. n. Greatness; vastness, whether in a physical or a moral sense; grandeur.
2. n. Largeness of relation or significance; importance; consequence: as, in affairs of magnitude disdain not to take counsel.
3. n. Size, or the property of having size; the extended quantity of a line, surface, or solid; length, area, or volume.
4. n. Any kind of continuous quantity which is comparable with extended quantity. In this sense we speak of the magnitude of a velocity, force, acceleration, or other vector quantity; but we do not properly speak of a magnitude of heat, energy, temperature, sound, etc. The use of the word as a synonym of quantity, as in the following passage, is to be deprecated.
5. n. In astronomy, the brightness of a star expressed according to the numerical system used by astronomers for that purpose. In this sense magnitude translates Greek μέγεθος, used in the same sense in the Almagest, the expression being due to the fact that bright stars, by an effect of irradiation, look larger than faint ones. The brightest stars are said to be of the first magnitude, while those of the sixth magnitude are hardly noticed by casual observers in ordinary states of the sky. Since the brightness of stars has been measured photometrically, the interval between successive magnitudes has been defined by a constant ratio of brightness, which in the so-called absolute scale, now generally used, is 5√100, or 2.51.
6. n. In ancient prosody, the length of a syllable, foot, colon, or meter, expressed in terms of the metrical unit (primary time, semeion, or mora): as, a foot of trisemic magnitude; a colon of icosasemic magnitude.

Wiktionary

1. n. uncountable, countable The absolute or relative size, extent or importance of something.
2. n. countable An order of magnitude.
3. n. mathematics A number, assigned to something, such that it may be compared to others numerically
4. n. mathematics Of a vector, the norm, most commonly, the two-norm.
5. n. astronomy The apparent brightness of a star (on a negative, logarithmic scale); apparent magnitude
6. n. seismology A measure of the energy released by an earthquake (e.g. on the Richter scale).

GNU Webster's 1913

1. n. Extent of dimensions; size; -- applied to things that have length, breadth, and thickness.
2. n. (Geom.) That which has one or more of the three dimensions, length, breadth, and thickness.
3. n. Anything of which greater or less can be predicated, as time, weight, force, and the like.
4. n. Greatness; grandeur.
5. n. Greatness, in reference to influence or effect; importance.
6. n. (Astron.) See magnitude of a star, below.

WordNet 3.0

1. n. the property of relative size or extent (whether large or small)
2. n. a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10
3. n. relative importance