Source : Free On-Line Dictionary of Computing

time complexity
     
         The way in which the number of steps required by
        an {algorithm} varies with the size of the problem it is
        solving.  Time complexity is normally expressed as an order of
        magnitude, e.g. O(N^2) means that if the size of the problem
        (N) doubles then the algorithm will take four times as many
        steps to complete.
     
        See also {computational complexity}, {space complexity}.
     
        (1996-05-08)