Both characters contain the moon radical 月, fitting since 朦胧 often describes dim moonlight or hazy moonlit scenes. Picture a misty moon barely visible through clouds.
usage
Common collocations: 月色朦胧 (hazy moonlight), 睡眼朦胧 (sleepy-eyed), 朦胧的记忆 (hazy memory). Also used in literary criticism: 朦胧诗 refers to the 'Misty Poetry' movement of the late 1970s-80s.
