reĝisoro

A gift of a word, so let us say it plainly: a director is not a king-machine. Look at reĝisoro with an Esperantist's eye and you can see reĝo, a king, then -is-, then -or-. Every piece of that is wrong, and each is wrong in an instructive way.

Why each piece fails. -Is- is not a suffix at all; it is the past-tense verb ending, and endings only appear at the end of a word, which is what makes them endings. -Or- is not an Esperanto suffix either: the language builds agent nouns with -ist- and -ant- and has no -or-, so the -or in reĝisoro, direktoro, traktoro and motoro is Latin arriving pre-assembled. And reĝ- is not the root here at all. The root is reĝisor-, all seven letters of it, borrowed as a unit from French regisseur by way of Russian and German, which is why it has that unmistakably Slavic-cinema flavour.

The etymology does not rescue the guess either. French regisseur does go back to Latin regere, to rule, and so, at a considerable distance, does reĝo. But they arrived in Esperanto separately, centuries apart, through different languages, and a shared great-grandparent is not a morpheme. This is the same trap ilustri sets three pages earlier in this band.

The fence between the four directors. A reĝisoro directs a filmo or a teatraĵo: the one who tells the actors what to do. A direktoro directs an institution, a school or a company. An estro is a boss or head of anything, built from the Esperanto root estr-. A dirigento conducts an orchestra. English piles all four onto director and conductor and leaves you guessing; here the word tells you which building you are in.