What does the term nebulous refer to?

The term "nebulous" refers to something that is vague or unclear. In this context, it describes ideas, concepts, or situations that lack definitive outlines or clarity. When something is described as nebulous, it often conveys a sense of ambiguity or indistinctness, making it difficult to grasp or understand fully.

The other choices, while suggesting clarity or precision—definite, clear, and specific—are all in direct contrast to what nebulous represents. Therefore, selecting the term that describes something as vague aligns perfectly with the meaning of "nebulous."