The term also, by extension, usually refers to the maximum-speed state of running the engine, as the normal result of a fully opened throttle plate/butterfly valve.
(Carburetors and fuel injection systems are arranged so as to provide the correct air–fuel ratio as conditions dynamically shift.)
In both control theory (involving humans and machines) and control logic (as a machine-based application thereof), the concept of wide open throttle can be divided logically into operator intent, throttle position itself, the resultant/net effect on the state of engine running at each moment, and the feedback loops among those factors.
This is true even in a system without electronic control, as, for example, when the operator holds the throttle open (pedal floored) to overcome flooding in a carbureted engine.
In electronic control, the feedback between the factors can be finessed and exploited in countless ways, even to the extent that in drive by wire systems the operator's input (which is pedal position) is a completely separate concern from throttle position itself, and the computer constantly makes new decisions about how the two should be correlated when the state of engine running changes from second to second.