‘叹吁’ is a literary, somewhat formal verb meaning 'to sigh'—specifically, to emit a soft, audible sigh expressing sorrow, weariness, regret, or deep emotion. Though composed of two characters (叹 and 吁), both individually meaning 'to sigh', they combine into a single disyllabic verb with heightened expressive weight and poetic resonance. Unlike the more common standalone 叹 (tàn), 叹吁 carries an elevated, often melancholic tone and appears frequently in classical poetry, modern essays, and formal writing—not in casual speech.

This word evokes a drawn-out, heartfelt exhalation, suggesting emotional gravity rather than momentary frustration. It’s often used with subjects like poets, elders, or observers reflecting on loss, injustice, or the passage of time. Because it’s literary, learners should avoid using it in everyday conversation; instead, reserve it for written expression or dramatic narration where emotional depth and stylistic refinement are intended.