dishonesty
Not being truthful on purpose, like lying or cheating.
Dishonesty is when someone deliberately hides the truth, misleads others, or says things they know aren't true. A student who copies homework and claims they did it themselves is being dishonest. A friend who breaks your toy and says they didn't touch it is being dishonest. Someone who exaggerates wildly about their accomplishments to impress others is being dishonest.
Dishonesty is different from simply being wrong or making a mistake. If you genuinely believe your answer is correct but it turns out you're mistaken, that's not dishonesty. Dishonesty requires knowing the truth but choosing to hide it or twist it anyway. It's the difference between getting a math problem wrong because you miscalculated (an honest mistake) and copying someone else's work and pretending it's yours (dishonest).
People are dishonest for different reasons. Sometimes they're afraid of getting in trouble, so they lie about breaking a window. Sometimes they want something they haven't earned, so they cheat on a test. Sometimes they want to avoid disappointing someone, so they make up excuses instead of admitting the truth.
Dishonesty destroys trust. Once people catch you in a pattern of dishonesty, they may stop believing you even when you're telling the truth.