This is the 797th most frequent Chinese word.
第四
"第四" means "fourth."
Ordinal number indicating the sequence of days within a specified period.
今年暑假的第四天，我们去海边玩了。
On the fourth day of this summer vacation, we went to the beach for fun.
Ordinal number used to specify the sequence of chapters in a book or text.
第四章讲的是概率论的基本定义。
The fourth chapter discusses the basic definitions of probability theory.
Ordinal number indicating a rank or positioning in a competitive setting.