Reference.com is the question answering service that delivers the best answers from the web and real people all in one place..Reference definition is the act of referring or consulting. How to use reference in a sentence..Usage Note Though originally a noun, reference is often used as a transitive verb meaning “to supply a book, article, or other work with references.” People also use the verb to mean “To cite as a reference” or simply “To mention or allude to.”.Reference definition, an act or instance of referring. See more. to arrange notes, data, etc. for easy reference Statistical data is referenced in the glossary..