When it comes to describing a slope, there are numerous synonyms to choose from. "On an incline" itself could be rephrased as "on a slant," "on a gradient," or "on a grade." Other synonyms for an incline might include "ascending" or "uphill," while the opposite, a decline, could be described as "descending" or "downhill." "Sloping" or "angled" might also be helpful to use, depending on the context. Identifying a specific type of incline, such as a hill or mountain, could also convey a similar meaning. By choosing the most appropriate synonym, writers and speakers can ensure that their descriptions are clear and effective.