A bald man is a man.
A one-legged man is still a man, even if in all medicine books the body of a man is shown with two legs.
How about a fictional man? Or a robotic man? An AI man? A virtual man?
Seriously?
Is a non-car a car?
Is a carrot a car?
We are at this point?
If you had read any of the circuit theory or general engineering books I have given you would know that in order to be part of the set --- let's call "all resistor" the elements need to share a common trait. Like when in that video for kids you have all vegetables in one set and all fruits in another set (and don't bring out the tomato!).
So, what is the common trait shared by the elements of the set "all resistors"? It's that they are fully characterized by a relationship between voltage and current. Only between V and I. Not q and V (those are capacitors) and not phi and I (those are inductors).
So, "all resistors" have a characteristic that is implicitly defined by f(v, I)=0, that is a curve in the vi plane.
Now, among all these resistors, some have a curve that is a straight line, that is a v + b I = 0, which you can rewrite as v = R I. This is the subset "linear resistors" of the set "all resistors". It is a very important set because it has all the easy to understand properties of linear functions, including superposition. That is why we strive to make our components the more linear possible (yes, the five striped thingies called "resistors" you can buy are actually nonlinear and can only be considered linear within specified limits). Since they are so easy to understand, we teach about them in high school and we simply call them "resistors" not to overload feeble minds with unnecessary complications
But the set "(linear) resistors" is not the entire set "all resistors". We are left with all those components that are described by a VI characteristic that is NOT linear, like diodes, scrs, mov, incandescent lamps, neon bulbs... These form the huge subset "nonlinear resistors" of the larger set "all resistors". So, they are resistors with f(v,I) nonlinear.
And no, a carrot is not a car.