身体

身体 (shēntǐ) means both 'body' and 'health' — two senses English splits into separate words but Chinese fuses into one. Concretely it is the physical body (身体很高 'tall body'), but in everyday conversation it more often means general health: 你身体好吗? is not 'is your body good?' but 'how is your health?' / 'how are you?'

Compared with English, 身体 is the default polite check-in for wellbeing, especially with older people; saying 注意身体 ('take care of your health') as you part ways is as common as 'take care' in English. For medical conditions and clinical states, switch to 健康 (jiànkāng, 'healthy / health' as a more formal noun). 身体 is also the word a doctor will ask about: 你身体哪儿不舒服? ('Where on your body is uncomfortable / what's wrong?').