"To guide, control, or direct (a vehicle)."

My car has driver assistance features, it can do basic lane keeping, keep a set distance behind the car in front (even in stop and go traffic), and has emergency braking assistance. But no one would say that it's self-driving.

Tesla FSD can control the car from entering the highway to taking your exit (plus some support for driving on smaller streets).

But it's not autonomous, hands-free driving.

Taking the dictionary definition of fully:

"completely or entirely; to the fullest extent"

I would expect a fully self-driving car to drive for the entirety of any trip I wish to take. Anything less than that I would consider as "partial".

My car has limited self-driving, it can only do limited lane keeping or keeping distance from the car in front.

By that definition self-parking cars can also fully self-drive.

My definition of driving is being able to do all the tasks required to pass a driving test, i.e. driving around a city (intersections, roundabouts etc.), motorway, country road and car parks.