The opposite of "nonsense" is "sense." When something makes sense, it is logical, reasonable, and understandable. It refers to ideas or statements that are supported by evidence, facts or data. By contrast, nonsense connotes ideas that lack coherence or logic, ideas that are irrational or illogical. Other antonyms for "nonsense" include rational, grounded, logical, coherent, and sound. These words describe ideas that can be understood and applied to real-life situations in meaningful ways. In short, the opposite of nonsense is something that is rational, sound or logical.