The word "冥思苦想" is formed by the juxtaposition of two two-character phrases: "冥思", where 冥 means deep or profound and 思 means to think, conveying deep thought, and "苦想", where 苦 means hard or bitter and 想 means to think, conveying hard thinking; combined, they reinforce each other to express the concept of engaging in intense, difficult contemplation.