1. A systematic plan of action: “Did you ever carry out your scheme of writing a series of sonnets embodying all the great epochs of art?”(Edith Wharton).
2. A secret or devious plan; a plot. See Synonyms at plan.
3. An orderly combination of related parts: an irrigation scheme with dams, reservoirs, and channels.
4. A chart, diagram, or outline of a system or object.