aŭtoritato

Aŭtoritato is authority in the sense of standing: the weight a person's word carries, and by extension the body that holds power. Potenco is the raw ability to make things happen, povo the capacity to do a particular thing, and aŭtoritato the recognised right to be obeyed. A tyrant has potenco without aŭtoritato; a retired professor may have the reverse.

Here is the trap, and it is one of the better ones in the language. Aŭto is a car. Aŭtoritato is not aŭto plus anything - there is no root ritato, and no amount of squinting will make a car into a source of authority. What has happened is that two unrelated things have collided on the same letters.

The Greek prefix aŭto- means "self", and it is real and productive: aŭtomata, aŭtobiografio, aŭtomobilo. Aŭto the car is a clipping of that last one, so the vehicle only owns those four letters by accident of abbreviation. Aŭtoritato, meanwhile, is Latin all the way down, from auctor and augere, and its aŭ has nothing to do with the Greek prefix at all. Three separate things, one spelling. The pronunciation gives no help either, since aŭ is a single diphthong in all of them.

Take this as the general lesson about borrowed roots: an international word arrives whole, and its internal shape is a fact about the language it came from, not an instruction for taking it apart here.