The word "模糊不清" is formed by directly combining the adjective "模糊", meaning blurred or vague, with the negative phrase "不清", meaning not clear. "模糊" conveys indistinctness through characters originally related to models and paste, while "不" negates "清", which denotes clarity. This juxtaposition intensifies the sense of ambiguity by redundantly emphasizing a lack of clear definition.