'Tóu yùn' literally means 'head dizziness' — combining 头 (tóu, 'head') and 晕 (yùn, 'dizzy' or 'giddy'). It describes the physical sensation of lightheadedness, unsteadiness, or spinning, often caused by low blood sugar, dehydration, motion, illness, or fatigue. Unlike abstract emotional states, 头晕 is strictly physiological and refers to a bodily symptom rather than a mood or mental condition.

This word is commonly used in everyday health-related conversations — for example, when describing how one feels upon standing up too quickly, riding in a car, or recovering from a cold. It's neutral in register and appropriate in both casual and clinical contexts, though in formal medical settings, doctors may specify underlying causes (e.g., vertigo or hypotension). It functions predicatively ('I feel dizzy') or attributively ('a dizzy spell'), but is rarely used as a standalone noun without modification.