Dissonance is a clashing or jarring combination of sounds that feels unpleasant or unsettled to your ears. In music, dissonance happens when notes played together create tension rather than harmony. If you've ever heard someone play wrong notes on a piano at the same time, creating a harsh, uncomfortable sound, that's dissonance. Composers sometimes use dissonance on purpose to create drama or unease in their music, then resolve it with harmonious notes that feel like relief.

The word also describes any kind of clash or inconsistency. Cognitive dissonance is when you hold two conflicting beliefs at the same time, which creates mental discomfort. For example, you might experience cognitive dissonance if you believe honesty is important but find yourself tempted to lie to avoid getting in trouble. Your brain feels the clash between what you believe and what you're considering doing.

The opposite of dissonance is consonance, which describes sounds or ideas that fit together smoothly and pleasantly. While dissonance creates tension and unease, consonance brings harmony and resolution.