What does REFERENCE mean?

noun

1. a remark that calls attention to something or someone“she made frequent mention of her promotion”
2. a short note recognizing a source of information or of a quoted passage“the student's essay failed to list several important citations”
3. an indicator that orients you generally“it is used as a reference for comparing the heating and the electrical energy involved”
4. a book to which you can refer for authoritative facts“he contributed articles to the basic reference work on that topic”
5. a formal recommendation by a former employer to a potential future employer describing the person's qualifications and dependability“requests for character references are all too often answered evasively”
6. the most direct or specific meaning of a word or expression; the class of objects that an expression refers to“the extension of `satellite of Mars' is the set containing only Demos and Phobos”
7. the act of referring or consulting“reference to an encyclopedia produced the answer”
8. a publication (or a passage from a publication) that is referred to“he carried an armful of references back to his desk”