怨气 (yuàn qì) literally combines 怨 (yuàn), meaning 'resentment' or 'grievance', and 气 (qì), meaning 'energy' or 'vital force'. Together, they form a noun describing deeply suppressed, lingering resentment — not just momentary anger, but a heavy, simmering emotional buildup that often goes unexpressed. This word carries a strong connotation of injustice felt over time, sometimes accumulating in silence until it affects one’s mood, health, or relationships.

It’s commonly used in psychological, interpersonal, or traditional Chinese medicine contexts — for instance, when describing how long-held grievances may manifest as physical discomfort or emotional withdrawal. Unlike general anger (生气), 怨气 implies passive endurance rather than outward confrontation, making it culturally resonant in contexts where direct complaint is discouraged. It’s often paired with verbs like 积累 (jīlěi, 'to accumulate'), 发泄 (fāxiè, 'to vent'), or 消 (xiāo, 'to dispel').