noun A beginning or introductory portion that comes before the main text of a document or book, typically serving to contextualize or explain the writing of the book and sometimes to acknowledge others' contributions; especially, such a discussion written by the work's own author.
The book included a brief preface explaining the author's motivations for writing.
noun An introduction, or series of preliminary remarks.
noun A variable prayer forming the prelude or introduction to the Eucharistic Prayer or canon of the Mass, following the Sursum corda dialogue and leading into the Sanctus.
noun A title or epithet.
verb To introduce or make a comment before (the main point); to premise.
Let me preface this by saying that I don't know him that well.