magnitude

noun

• 1the great size or extent of something:they may feel discouraged at the magnitude of the task before them
• great importance:events of tragic magnitude

• 2size:electorates of less than average magnitude
• a numerical quantity or value:the magnitudes of all the economic variables could be determined

• 3the degree of brightness of a star. The magnitude of an astronomical object is now reckoned as the negative logarithm of the brightness; a decrease of one magnitude represents an increase in brightness of 2.512 times. A star with an apparent magnitude of six is barely visible to the naked eye. See also apparent magnitude, absolute magnitude.
• the class into which a star falls by virtue of its brightness.
• a difference of one on a scale of brightness, treated as a unit of measurement.