The Collaborative International Dictionary of English v.0.48:

Median \Me"di*an\ (m[=e]"d[i^]*an), a. [L. medianus, fr. medius
   middle. See Medial.]
   1. Being in the middle; running through the middle; as, a
      median groove.
      [1913 Webster]

   2. (Zool.) Situated in the middle; lying in a plane dividing
      a bilateral animal into right and left halves; -- said of
      unpaired organs and parts; as, median coverts.
      [1913 Webster]

   Median line.
      (a) (Anat.) Any line in the mesial plane; specif., either
          of the lines in which the mesial plane meets the
          surface of the body.
      (b) (Geom.) The line drawn from an angle of a triangle to
          the middle of the opposite side; any line having the
          nature of a diameter.

   Median plane (Anat.), the mesial plane.

   Median point (Geom.), the point where the three median
      lines of a triangle mutually intersect.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Median \Me"di*an\, n. (Geom.)
   A median line or point.
   [1913 Webster]

WordNet (r) 3.0 (2006):

median
    adj 1: relating to or constituting the middle value of an
           ordered set of values (or the average of the middle two
           in a set with an even number of values); "the median
           value of 17, 20, and 36 is 20"; "the median income for
           the year was $15,000" [syn: median(a), average]
    2: dividing an animal into right and left halves [syn: medial,
       median]
    3: relating to or situated in or extending toward the middle
       [syn: median, medial]
    n 1: the value below which 50% of the cases fall [syn: median,
         median value]