What is another word for secret plan?
Pronunciation: [sˈiːkɹət plˈan] (IPA) 
If you're in need of some synonyms for the phrase "secret plan," there are plenty of options to choose from. You could use the term "covert scheme," which implies a hidden or undercover plan. "Subterfuge" is another option, which suggests a plan that relies on deception or trickery. "Conspiracy" could also work, particularly if the plan involves multiple people working together in secret. Other potential synonyms include "plot," "machiavellian strategy," "clandestine operation," or "cloak-and-dagger plan." Ultimately, the best synonym will depend on the context and tone of your writing, as well as the specific nuances you want to convey about the plan in question.
