Definitions of reference:

• noun:   the act of referring or consulting

  Example: "Reference to an encyclopedia produced the answer"

• noun:   the most direct or specific meaning of a word or expression; the class of objects that an expression refers to
• noun:   the relation between a word or phrase and the object or idea it refers to

  Example: "He argued that reference is a consequence of conditioned reflexes"

• noun:   a publication (or a passage from a publication) that is referred to

  Example: "He carried an armful of references back to his desk"

• noun:   a book to which you can refer for authoritative facts

  Example: "He contributed articles to the basic reference work on that topic"

• noun:   a formal recommendation by a former employer to a potential future employer describing the person's qualifications and dependability

  Example: "Requests for character references are all to often answered evasively"

• noun:   a remark that calls attention to something or someone

  Example: "The speaker made several references to his wife"

• noun:   an indicator that orients you generally

  Example: "It is used as a reference for comparing the heating and the electrical energy involved"

• noun:   a short note recognizing a source of information or of a quoted passage
• verb:   refer to

  Example: "He referenced his colleagues' work"