Source : Free On-Line Dictionary of Computing

learning curve
     
         A graph showing some measure of the cost of
        performing some action against the number of times it has been
        performed.  The term probably entered engineering via the
        aircraft industry in the 1930s, where it was used to describe
        plots showing the cost of making some particular design of
        aeroplane against the number of units made.
     
        The term is also used in psychology to mean a graph showing
        some measure of something learned against the number of
        trials.  The psychology graphs normally slope upward whereas
        the manufacturing ones normally slope downward but they are
        both usually steep to start with and then level out.
     
        {Marketroids} often misuse the term to mean the amount of time
        it takes to learn to use something ("reduce the learning
        curve") or the ease of learning it ("easy learning curve").
        The phrase "steep learning curve" is sometimes used
        incorrectly to mean "hard to learn" whereas of course it
        implies rapid learning.
     
        {Engineering
       
     (http://www.computerworld.com/cwi/story/0,1199,NAV47-68-85-1942_STO61762,00.html)}.
     
        {Psychology
        (http://sun.science.wayne.edu/~wpoff/cor/mem/opereinf.html)}.
     
        (2002-01-22)