The characters combine to create a vivid image: 图谋 (túmóu) means “to plan and conspire,” while 不轨 (bùguǐ) means “not on the track.” Together, the idiom means “to plot a course that is off the established tracks”—a conspiracy to break the rules.
This idiom is deeply rooted in a cultural context that values order, stability, and adherence to established norms (规矩, guīju). The concept of everyone staying on their “track” is fundamental to social harmony. Therefore, someone who 图谋不轨 is seen as a direct threat to this order.
This term highlights the cultural emphasis on collective stability over individual ambition when that ambition threatens the system.
图谋不轨 is a formal and serious term. You will not hear it in casual, everyday conversation unless used hyperbolically or as a joke.