The idea that money is worth more if received sooner rather than later....more on Time value of money
The idea that a dollar today is worth more than a dollar in the future, because the dollar received today can earn interest up until the time the future dollar is received.
The idea that a dollar today is worth more than a dollar in the future, because the dollar received today can earn interest up until the time the future dollar is received. 
Comparison of a lump sum of money, or a series of equal payments, between two different time periods
(TVM) The time value of money (TVM) is an economic principle that suggests present day money is worth less than money in the future because of its earning power over time.