(semantics) The condition of a sign which has an empty, absent, non-existent, paradoxical, hypothetical, supernatural, or undefined referent, such as nothing, null, vacuum, or void.

(data management) Data describing a physical or virtual object and its properties.

The list of sources used or considered in preparing a work.

plural of reference book

A book providing factual information. / (libraries) A book that can be consulted in the library but cannot be borrowed.

plural of reference work

(computing) A piece of software that implements a specification of requirements and whose main purpose is to help in the creation of other software implementations of the specification by serving as a point of reference rather than being put to directly productive use.

(programming) An evaluation strategy in which the arguments to a function are evaluated first, and a pointer to the result is passed to the function.

plural of point of reference

A statement concerning the character of a person, typically for submission during a job application or court proceeding.