Okay, the user wants me to translate "night-dress" into Traditional Chinese. Let me think about the correct term here. In Chinese, "night-dress" is commonly translated as "睡衣" which is the traditional character version. Since the user specified that if the content is already in Traditional Chinese, I should leave it unchanged. But "night-dress" is an English word, so I need to translate it. The translation should be "睡衣" which is the correct term for nightwear in Traditional Chinese. I should make sure there's no explanation, just the translation. Let me double-check to confirm that there's no other possible translation. Yep, "睡衣" is the standard term. Alright, that's the answer.