心力交瘁 literally means 'heart and strength mutually exhausted' — '心' (xīn) refers to the mind or spirit, '力' (lì) means physical strength or energy, '交' (jiāo) indicates mutual or simultaneous occurrence, and '瘁' (cuì) means exhaustion or debilitation. Together, the phrase vividly describes a state of total depletion — where both mental and physical resources are completely drained, often after prolonged stress, overwork, caregiving, or emotional hardship.

This is a formal, literary idiom commonly used in written Chinese and serious spoken contexts (e.g., news reports, medical discussions, or personal reflections). It carries strong connotations of burnout and profound weariness — stronger than everyday terms like 累 (lèi, 'tired') or 疲劳 (píláo, 'fatigue'). It’s rarely used lightly; saying someone is 心力交瘁 implies they’re at a breaking point, not just sleepy or busy.