When it comes to borderline cases, there are a variety of synonyms that can be utilized. Some examples include marginal, questionable, on the edge, on the cusp, borderline situation, borderline state, and ambiguous. These words all convey the idea that the situation is not completely clear-cut and requires careful consideration. They can be used in a variety of contexts, from medical diagnoses to legal disputes. Whatever the situation, using a synonym for "borderline case" can help to emphasize the importance of careful analysis and thoughtful decision-making in order to determine the best course of action.