A medial part (as a vein or nerve); a value in an ordered set of values below and above which there is an equal number of values or which is the arithmetic mean of the two middle values if there is no one middle number; a vertical line that divides the histogram of a frequency distribution into two parts of equal area; a value of a random variable for which all greater values make the cumulative distribution function greater than one half and all lesser values make it less than one half; a line from a vertex of a triangle to the midpoint of the opposite side.