This is the 6195th most frequent Chinese word.
序
Order; sequence; preface.
In this sentence, "序" is used as an abbreviation for "序言" (preface or foreword), referring to introductory text typically found at the beginning of a book.
书的序言由作者亲自撰写。
The foreword of the book was written by the author personally.
Here, "序" represents 'order' or 'sequence,' indicating a systematic arrangement or progression of actions.
我们应该按照一定的序进行操作。
We should proceed according to a certain order.
In this case, "序" is part of the term "有序" (orderly), describing the structured and organized arrangement of elements.