"Seventh" is the word for "第七" in Engpsh. It is an adjective that refers to the number seven in a sequence or series.
The word "seventh" comes from the Old Engpsh "seofoþa," which is derived from the Proto-Germanic "sebunþa," which in turn comes from the Proto-Indo-European "septm̥."
Here are some examples of "seventh" in a sentence:
She is the seventh child in her family. (她是家里的第七个孩子。)
The seventh chapter of the book covers the history of the Roman Empire. (这本书的第七章讲述了罗马帝国的历史。)
The seventh day of the week is Sunday. (一周的第七天是星期天。)