A dipole is an electronic component that has two poles (two terminals). If one uses I to represent the current that enters via one terminal and exits via the other, and V to represent the voltage between the terminals, one defines the “characteristic of the dipole” as the function that relates I and V. This animation illustrates graphical representations of these functions for 4 typical electronic components.
A characteristic I = f(V) does not depend on time. The quantities I and V are continuous ones (DC).