食欲 (shí yù) is the formal, written word for 'appetite' — the desire for food. It is more clinical than 胃口 (wèi kǒu), which is the everyday spoken term and can also mean 'liking' or 'taste' in a figurative sense (e.g., 'to one's liking'). Unlike 欲望 (yù wàng), which refers to any general desire or craving, 食欲 is specific to eating.