Anything related to voltage-current characteristic curves, a.k.a. V-I characteristics or V-I curve.
A V-I curve is a graphical representation of the relationship between current and voltage used to describe the behavior of resistive (a.k.a. non-reactive) components, like semiconductor diodes or other non-linear 2-terminal devices.
The same terminology applies also to devices with more terminals, although now often there is a third quantity involved and the characteristic curve becomes a family of curves.