Monotonicity is a property of certain types of digital-to-analog converter ( DAC ) circuits. The analog output never decreases during the input sequence. If the analog output decreases at any point during the input sequence, a DAC is said to be non-monotonic.
In this way, what is a monotonic function?
A monotonic function is a function which is either entirely nonincreasing or nondecreasing. A function is monotonic if its first derivative (which need not be continuous) does not change sign.