The word "labent" is not a very common word in everyday vocabulary which refers to something that is slipping or sliding. However, there are many synonyms that can be used to convey the same meaning such as gliding, skidding, slipping, sliding, or flowing. Each of these words has a slightly different connotation, for example, "gliding" usually refers to the movement of something through the air, while "slipping" and "skidding" suggest a loss of traction on a surface. Using synonyms can help to add variety and interest to writing, and convey a precise meaning to the reader.