Codswallop is a slang term that refers to nonsense. Its antonyms include legitimate, factual, and sensible. These words convey the idea of credibility, reliability, and reasonableness, which are the opposite of codswallop. Other antonyms for codswallop are truth, authenticity, and sincerity. These words highlight the importance of honesty and truthfulness, which are lacking in codswallop. Additionally, antonyms for codswallop could also include logic, reason, and rationality. These words emphasize the need for logical and reasonable explanations and ideas rather than unfounded and baseless ones. Overall, antonyms for codswallop can help us distinguish between what is true and what is absurd.