kortego

This one is a genuine build, and a delight, because the pieces are both familiar and the result is not obvious until you see it.

Korto is a yard: the open space enclosed by the buildings of a house or a farm. -Eg- is the augmentative, the suffix that makes things big and intense - pordo a door, pordego a gate; varma warm, varmega scalding. Put them together and you get a great yard, which is exactly what a royal court once was: the enclosure round the palace and everybody in it. Kortego is the retinue of a monarch or a prince, and a kortegano is a courtier.

The delightful part is that this is not Esperanto being clever. Latin did it first. Cohors was a farmyard and then, by the same widening, an emperor's household - which is why English inherited "court" for both a tennis court and the Court of St James's. Zamenhof rebuilt the metaphor out of parts a learner already owns, and the augmentative article will tell you the rest of what -eg- does.

One thing it does not mean. A court of law is not a kortego. That is tribunalo, which sits at rank 2032 just ahead of this word, or juĝejo, literally a judging-place. English lets one word cover the monarch's household and the judge's bench because both really did meet in the same royal yard; Esperanto separates them, and a sentence about la kortego is about crowns and courtiers, never about a trial.