Uneatable describes food that you cannot bring yourself to eat — it is burnt, rotten, far too salty, or just horrible. Here is the interesting part, and the reason dictionaries mark this word with a warning: English already has inedible, which most people prefer, and some careful speakers and editors say uneatable is simply a mistake. It is not a mistake — it has been in English for centuries and good writers use it — but you should know the argument exists, because a teacher or an examiner might mark it. The two words also lean in slightly different directions. Inedible is the wider and more scientific one: it covers things that are not food at all, or that would poison you (inedible mushrooms, an inedible plastic wrapper). Uneatable leans toward disgust rather than danger — the food is technically food, but it tastes so bad that eating it is out of the question. There is a famous English joke about fox hunting that plays on exactly this pair, so native speakers do feel the difference. For your own writing, the safe choice is inedible. Keep uneatable for when you want that note of 'I tried, and I could not'.

難吃到吃不下去的、不能入口的。跟 inedible（不可食用、有毒或根本不是食物）不同：uneatable 偏向「東西是食物沒錯，但難吃到吃不下」。台灣同學要用一個一定安全的字，就用 inedible。