Planning something secretly or dishonestly, usually to gain advantage or harm someone.
From 'scheme' (from Greek skhēma meaning 'form' or 'shape'), which entered English via Latin and French. The meaning shifted from neutral 'a plan' to specifically 'a deceptive plan' by the 1700s.
The word 'scheme' originally just meant any organized plan or design—mathematicians use it that way still—but because people use plans to deceive each other so often, the word became almost automatically suspicious over centuries of usage.
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