Guile is the clever, quiet kind of dishonesty: you do not smash your way through; you twist, hide, and trick so that someone believes the wrong thing. It is usually uncountable — we say a person has guile, uses guile, or is full of guile, not 'a guile'. The word feels a little literary, a little old-fashioned, but it is still alive. A news writer might talk about political guile; a storyteller might give a fox or a trickster guile. In ordinary talk, students more often hear sneaky, cunning, or sly. Though actually, guile is not always a cartoon-villain word. People sometimes use it with a thin smile, as if the cleverness were almost impressive — but the core is still deception, not honest skill. There is an old verb to guile, meaning to deceive, but you will almost never meet it now; the noun is the one that lives.