noun, verb, -aced, -ac⋅ing.| 1. | a preliminary statement in a book by the book's author or editor, setting forth its purpose and scope, expressing acknowledgment of assistance from others, etc. |
| 2. | an introductory part, as of a speech. |
| 3. | something preliminary or introductory: The meeting was the preface to an alliance. |
| 4. | Ecclesiastical. a prayer of thanksgiving, the introduction to the canon of the Mass, ending with the Sanctus. |
| 5. | to provide with or introduce by a preface. |
| 6. | to serve as a preface to. |