The Chinese word 疲惫 is a synonymous compound (并列结构) formed by combining two characters with similar meanings to reinforce a single concept. The first character, 疲 (pí), originally depicted illness-related fatigue, and the second, 惫 (bèi), conveys extreme mental or physical exhaustion. Together, they create a stronger, more nuanced term than either character alone, specifically describing a state of being completely worn out, both physically and mentally, from prolonged strain or hard work. This method of pairing near-synonyms is a common and classical way of forming words in Chinese to express abstract qualities with precision.