呕吐 is a verb meaning 'to vomit' — the involuntary expulsion of stomach contents through the mouth. It combines two characters, both of which can mean 'to expel': 呕 (ǒu) often implies retching or heaving, while 吐 (tù) means 'to spit out' or 'to expel'. Together, they form a compound verb emphasizing forceful, often distressing, bodily expulsion. This word is used primarily in medical, clinical, or descriptive contexts — for example, when reporting symptoms, diagnosing illness, or describing physical reactions to food, motion, or stress.

The term is neutral in register but tends to appear in formal or serious situations rather than casual speech; native speakers might use softer alternatives like 恶心 (feeling nauseous) or 反胃 (nausea) before actual vomiting occurs. 呕吐 can also function as a noun ('an episode of vomiting'), though its verbal usage is far more common. It is frequently paired with words like 感 (feeling), 症状 (symptom), or 时 (when), as in 呕吐时 (when vomiting).