Silk line, most commonly associated with fishing, can have several antonyms depending on the context. For instance, if silk line is used to denote a luxury brand or product, its antonyms would be budget, economy, or low-cost. However, if it is used to refer to the thin and smooth thread used in fishing, its antonyms would be rough or rugged fishing line. Additionally, if we look at the word Silk, its antonyms would include rough, coarse, and scratchy. Overall, the antonyms for silk lines would vary depending on the context and the meaning attributed to it.