Scheme
mid 16th century (denoting a figure of speech): from Latin schema, from Greek (see schema). An early sense was ‘diagram of the position of celestial objects’, giving rise to ‘diagram, outline’, whence the current senses. The unfavourable notion ‘plot’ arose in the mid 18th century.
wiktionary
From Medieval Latin schēma(“figure, form”), from Ancient Greek σχῆμα(skhêma, “form, shape”), from ἔχω(ékhō, “I hold”). Doublet of schema. Compare sketch.
etymonline
scheme (n.)
1550s, "figure of speech," from Medieval Latin schema "shape, figure, form, appearance; figure of speech; posture in dancing," from Greek skhema (genitive skhematos) "figure, appearance, the nature of a thing," related to skhein "to get," and ekhein "to have, hold; be in a given state or condition," from PIE root *segh- "to hold."
The sense "program of action" first is attested 1640s. Unfavorable overtones (selfish, devious) began to creep in early 18c. Meaning "complex unity of coordinated component elements" is from 1736. Color scheme is attested from 1884.
scheme (v.)
"devise a scheme," 1767 (earlier "reduce to a scheme," 1716), from scheme (n.). Related: Schemed; scheming.
