‘序言’ (xù yán) is a noun meaning 'preface' or 'foreword'—the introductory section written by the author or another person at the beginning of a book, report, or formal document. The character 序 (xù) means 'order', 'sequence', or 'introduction', suggesting something that comes first in a logical or structural arrangement. The character 言 (yán) means 'speech' or 'words', indicating spoken or written expression. Together, 序言 literally conveys 'introductory words'—a short, reflective text that sets the context, purpose, or background for what follows.

This term is commonly used in academic, literary, and publishing contexts. It is more formal than everyday speech and appears almost exclusively in written works—not in casual conversation. While similar to 引言 (yǐn yán), 序言 typically implies a broader, more personal or authoritative introduction, often written by someone other than the main author (e.g., a respected scholar introducing a colleague’s work).