Source : Webster's Revised Unabridged Dictionary (1913)

Consumer's surplus \Consumer's surplus\ (Polit. econ.)
   The excess that a purchaser would be willing to pay for a
   commodity over that he does pay, rather than go without the
   commodity; -- called also

   {consumer's rent}.

            The price which a person pays for a thing can never
            exceed, and seldom comes up to, that which he would
            be willing to pay rather than go without it. . . .
            The excess of the price which he would be willing to
            pay rather than go without it, over that which he
            actually does pay, is the economic measure of this
            surplus satisfaction. It has some analogies to a
            rent; but is perhaps best called simply consumer's
            surplus.                              --Alfred
                                                  Marshall.