The word 诡计 is formed by combining two characters whose core meanings merge to create a new, unified concept. 诡 (guǐ) carries connotations of deceitfulness, cunning, and something strange or abnormal. 计 (jì) fundamentally means a plan, scheme, or calculation. When fused, the deceitful, slippery quality of 诡 directly modifies and corrupts the neutral idea of a plan in 计, resulting in a compound that inherently means a treacherous scheme, a cunning plot, or a dishonest trick. The formation is not merely additive; the first character injects a specific, negative moral character into the second, creating a seamless idea of a plan born from deception.