The deciding of what acts when, across many parts. Orchestration produces nothing itself and everything depends on it.
From Greek ὀρχήστρα (orkhēstra, the dancing-space of the chorus), via orchestra and the 19th-century verb orchestrate; the deciding of what happens when, across many parts moving on one floor.
The deciding of what happens when across many parts. It produces nothing on its own, and everything else depends on it getting the timing right.