Forward means in the direction that you are facing or in the direction that you are travelling. As an extension, it means travelling or moving onward/ahead (literally or metaphorically – “the convoy moved forward across the plain” / “forward-thinking has enabled us to plan the future”), in the standard order (“the purchasing process is going forward”), and then further advanced than would be expected (“she is forward in her reading”). It has additional meanings of the front of a ship; being a bit bold and over-familiar (“she was very forward and flirted with all of the sailors as she served their drinks”); and sending on a letter from one address to a final destination (“When he was at university, his parents thoughtfully forwarded all of his junk mail to him”).
A foreword, which is the word that our author clients were looking for, is a short introduction to a book, which is usually written by somebody other than the author of the book – a celebrity or someone more experienced in the field.
While the foreword might be considered to go at the forward end of a book, it’s a fore word, as in words that come before.