吐气 literally means 'to expel breath' — 吐 (tǔ) means 'to spit out, to emit', and 气 (qì) means 'air, breath, or vital energy'. Together, 吐气 refers first and foremost to the physical act of exhaling, especially in contexts like breathing exercises, meditation, or medical instructions. It is commonly used in health-related discussions about respiration, qigong, or yoga.

Figuratively, 吐气 carries a strong emotional connotation: releasing long-held frustration, anger, or stress — as if 'blowing off steam'. This usage often appears in idioms like 吐气扬眉 (tǔ qì yáng méi), meaning 'to feel vindicated and proud after overcoming hardship'. Unlike neutral terms like 呼气 (hū qì), 吐气 emphasizes intentionality and emotional relief, making it more expressive and context-sensitive.