Which term describes a person who is sly and deceitful?

The term "wily" specifically refers to someone who is clever in a way that is often devious or deceitful. A wily individual is skilled at using their intelligence to manipulate situations or people, often for their own advantage. This word carries connotations of cunning and a tendency to employ trickery, making it the perfect descriptor for someone who is sly in nature.

On the other hand, the other options present characteristics that are quite the opposite. For instance, "candid" describes someone who is honest and straightforward, lacking the slyness or duplicity that "wily" implies. "Trustworthy" refers to a person who is reliable and deserving of trust, clearly not aligning with the idea of deceitfulness. Lastly, "open-hearted" denotes a person who is generous and sincere, which again stands in stark contrast to the sly and cunning nature associated with being wily. Thus, wily is the only term that accurately captures the essence of someone who operates in a sly and deceitful manner.