skemo

A false friend, and an unusually clean one. English scheme has soured. Outside a few fixed phrases like pension scheme it now means a plot, a dodge, something a schemer is up to. Esperanto skemo has none of that: it is a diagram, a simplified drawing, an outline that strips a thing down to its structure so you can see how it works. There is nothing shifty about a skemo, and translating "he had a scheme" as li havis skemon puts a wiring diagram where you meant a conspiracy. For the English sense reach for intrigo, komploto or ruzo.

Nor is it a plano. A plan is a sequence you intend to carry out; a skemo is a picture of how something is arranged. The two overlap in English and stay apart here. Where a skemo differs from a bildo is that it is deliberately unfaithful: it throws away scale, colour and detail, and keeps only the relationships. A circuit diagram is the purest case.

No hidden seam. Skem- is one root, and the -em- a reader might spot inside it is not the suffix of inclination that gives laborema and kolerema, because that suffix attaches after a root rather than inside one. Skema is the adjective, schematic, and skeme means in outline, which is a useful thing to say about an explanation you are about to give.