truko

Not a small hole. Truo is a hole, and Esperanto has plenty of nouns ending -ko, so truko invites a cut that does not exist. It is one root, French truc, and it has nothing to do with holes. Nor with trui, to make a hole in something, which is a real verb you can build from truo and will occasionally meet. The two words sit next to each other in the dictionary and share no ancestry at all.

What it covers. A truko is a device for getting a result you have not earned honestly, or at least not obviously: a conjuror's trick, a legal dodge, a trick of the trade, the gimmick that sells a product. It can be admiring (bona truko) or contemptuous (malnova truko), and the tone comes from the adjective rather than the noun.

The verb is somebody else's. You do not usually truki something; you trompi someone, which is to deceive or cheat. Keep the two apart: trompo is the deception as an act against a person, truko the clever mechanism, which may be perfectly innocent. A stage magician performs trukoj and deceives nobody, because everybody in the room has agreed to it.

Film and stage. In the language of cinema, trukoj are effects - wires, mirrors, editing - and the older Esperanto term for special effects is trukaj efektoj, which pairs this word with efekto three ranks along. Iluzio is what the audience gets; magio is what they are invited to pretend they saw.