Other forms: dishonesties
Acting in a way that's deceitful or false is dishonesty. If your best friend claims she'll be studying all weekend, but she's actually planning to go out with other pals, that's dishonesty.
The word dishonesty implies that someone's lying, but it also encompasses cheating or being deceptive. When a magician claims to have special powers but secretly hides cards up their sleeve, you might think of it as dishonesty — although the magician might call it "illusion" or "sleight of hand."