The antonyms for the word "under-done" could include well-done, fully cooked, overcooked, burned, and charred. When it comes to preparing food, the term "under-done" implies that it has not been cooked enough or thoroughly, which can result in health risks or an unpleasant taste. In contrast, "well-done" indicates that the food has been cooked thoroughly and completely, ensuring that it is safe to eat and tastes delicious. Overcooked, burned, and charred all refer to food that has been cooked beyond the recommended time, leading to a dry or burnt consistency. Utilizing the appropriate antonym will assist in ensuring the food is cooked to perfection.