Slicken is a term that typically refers to a slippery, smooth surface, often caused by the presence of water or oil. If you're looking for synonyms for slicken, there are several options that you might want to consider. For example, some possible alternatives might include terms like slick, slippery, greasy, oily, polished, or even gleaming. Other possibilities might include phrases like "well-lubricated," "mirror-like," or "shining." Ultimately, the choice of synonym will depend on the specific context in which you're using the term, as well as the overall tone and style of your writing. With a bit of creativity and careful consideration, you should be able to find the perfect word or phrase to convey your intended meaning, no matter what the situation might be.