A book can have more than three authors-- a book can have as many authors as contributed to the book. However, most publishers will ask to limit the authors' names to the fewest, with secondary authors listed on a front page.
She is excited to coauthor a research paper with her colleague.
"Coauthor" can be a noun or a verb. As a noun, it refers to someone who writes a book or article with another person. As a verb, it describes the act of writing a book or article with someone else.
It means that more than one author wrote a book/article together.
coauthor
no.
According to the sources I've found on a quick search, you should hyphenate 'coauthor', i.e., it would better be: "co-author".
Generally co-author should be hyphenated, but the relaxed rules of modern times often present coauthor as one word
Examples of co are cooperate, coworker, coauthor and so on.
the hatchet
The three people who showed Auggie around before school started in the book Wonder are Jack Will, Charlotte, and Julian.
johnjay
Three or more people edited the book.