“Dissonance is a musical term. It means things are not in harmony. Design dissonance occurs when a product or service sends out cognitive signals that run counter to the desired effect. In the strictest sense of the term, design dissonance often relates to usability – when a design somehow pushes a user in the wrong direction, in terms of both understanding and action. But in a broader sense, design dissonance can create disappointment, particularly when it occurs in relation to a service.”

(Eric Reiss a.k.a. @elreiss ~ UXmatters)