資料來源 : Webster's Revised Unabridged Dictionary (1913)

Mean \Mean\, a. [OE. mene, OF. meiien, F. moyen, fr. L. medianus
   that is in the middle, fr. medius; akin to E. mid. See
   {Mid}.]
   1. Occupying a middle position; middle; being about midway
      between extremes.

            Being of middle age and a mean stature. --Sir. P.
                                                  Sidney.

   2. Intermediate in excellence of any kind.

            According to the fittest style of lofty, mean, or
            lowly.                                --Milton.

   3. (Math.) Average; having an intermediate value between two
      extremes, or between the several successive values of a
      variable quantity during one cycle of variation; as, mean
      distance; mean motion; mean solar day.

   {Mean distance} (of a planet from the sun) (Astron.), the
      average of the distances throughout one revolution of the
      planet, equivalent to the semi-major axis of the orbit.

   {Mean error} (Math. Phys.), the average error of a number of
      observations found by taking the mean value of the
      positive and negative errors without regard to sign.

   {Mean-square error}, or {Error of the mean square} (Math.
      Phys.), the error the square of which is the mean of the
      squares of all the errors; -- called also, especially by
      European writers, {mean error}.

   {Mean line}. (Crystallog.) Same as {Bisectrix}.

   {Mean noon}, noon as determined by mean time.

   {Mean proportional} (between two numbers) (Math.), the square
      root of their product.

   {Mean sun}, a fictitious sun supposed to move uniformly in
      the equator so as to be on the meridian each day at mean
      noon.

   {Mean time}, time as measured by an equable motion, as of a
      perfect clock, or as reckoned on the supposition that all
      the days of the year are of a mean or uniform length, in
      contradistinction from apparent time, or that actually
      indicated by the sun, and from sidereal time, or that
      measured by the stars.