conniving
Sneaky and dishonest, secretly planning to trick others.
Conniving means scheming in a sneaky, underhanded way to get what you want, usually by tricking or manipulating others. A conniving person plots secretly to gain an advantage, often at someone else's expense.
Think of a student who connives to get out of a group project by pretending to be sick, leaving teammates to do all the work. Or imagine someone who connives to get their sibling in trouble by carefully arranging clues to make it look like the sibling broke a rule. In classic stories, conniving villains whisper secret plans to steal treasure or frame innocent people for crimes they didn't commit.
The word carries a strong negative feeling. Unlike simply being clever or strategic, conniving suggests dishonesty and selfishness. Someone might be smart enough to solve a difficult problem, but if they use that intelligence to trick others for personal gain, they're being conniving.
You might hear people talk about conniving politicians who make secret deals, or conniving characters in movies who smile to your face while plotting behind your back. The word emphasizes the sneaky, calculating nature of the scheming: a conniving person doesn't just want something, they're willing to deceive and manipulate to get it.