The word 呕吐 is formed through the repetition of meaning. Both characters, 呕 (ōu) and 吐 (tù), individually convey the idea of vomiting or disgorging from the mouth. 呕 often emphasizes the throat action and sound of retching, while 吐 focuses more on the act of expelling. By combining them, they create a single, reinforced concept that vividly depicts the full, visceral action of being sick, making the compound more expressive and emphatic than either character alone.