order of magnitude
 數量級 OM


 order of magnitude
      n 1: a degree in a continuum of size or quantity; "it was on the
           order of a mile"; "an explosion of a low order of
           magnitude" [syn: order]
      2: 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 [syn: magnitude]