‘晕机’ (yùn jī) literally combines ‘晕’ (yùn), meaning ‘dizzy’ or ‘nauseated’, and ‘机’ (jī), short for ‘飞机’ (fēijī, ‘airplane’). Together, it specifically refers to motion sickness caused by air travel — the dizziness, nausea, sweating, and discomfort some people experience during flight due to inner-ear imbalance and visual disorientation. It is a compound noun formed by combining a symptom with its trigger.

This term is commonly used in medical, travel, and everyday contexts — for example, when discussing pre-flight preparations, medication, or personal health concerns. Unlike general ‘晕车’ (car sickness) or ‘晕船’ (sea sickness), ‘晕机’ is narrowly focused on airplane-related motion sickness. It is neutral in register and widely understood across Mandarin-speaking regions.