Definitions of magnitude:

  • noun:   the property of relative size or extent
    Example: "They tried to predict the magnitude of the explosion"
  • noun:   relative importance
    Example: "A problem of the first magnitude"
  • noun:   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