What term describes a lack of agreement or harmony?

The term that best describes a lack of agreement or harmony is "discord." This word specifically refers to a state of disagreement or conflict, often characterized by tension and a lack of cooperation among individuals or groups. In various contexts, such as music or interpersonal relationships, discord implies that elements do not blend well together, resulting in a situation marked by disharmony.

Dissent refers to the expression of differing opinions or beliefs but does not inherently convey a sense of conflict like discord does. Dismay indicates a state of shock or disappointment, which is more about emotional response rather than a lack of agreement. A dispute generally involves a conflict or disagreement but often implies an argument or contest over a specific issue rather than the broader sense of disharmony represented by discord.