A pointer from one thing to another. A reference holds no content of its own — it holds a way to reach content.
Old French reference, from Medieval Latin referentia, from Latin referre (to carry back, to relate): re- (back) + ferre (to carry); a reference holds no content of its own — it holds only the carrying-back to where the content lives.
A pointer from one thing to another. The root's carrying-back is exact: a reference holds no content of its own, only a way to reach content that lives elsewhere.