The term "in fine fettle" means to be in good health, shape, or condition. The antonyms for this phrase could include words such as sickly, weak, frail, unwell, or debilitated. These words denote a state of poor health, weakness, or a general lack of vitality. Other antonyms may include words such as broken, damaged, or defective, which suggest a state of physical damage or malfunction. Additionally, words like disheveled, unkempt, or messy could be antonyms for "in fine fettle" to describe a state of untidiness, disarray, or disorderliness. Ultimately, the antonyms for "in fine fettle" describe a range of states that are the opposite of being healthy, robust, and strong.