The word 瞎说 is formed by combining two characters: 瞎, which originally means "blind" (derived from the radical for "eye" combined with a phonetic component suggesting impairment), and 说, meaning "to speak". The formation is conceptually metaphorical, directly painting the image of "speaking while blind", that is, talking without seeing the truth or reality, which naturally extends to the meaning of talking nonsense or making groundless statements. It’s a vivid, figurative compound where the first character modifies the action of the second through a concrete sensory metaphor.