reference has 19 distinct synonyms spread across 10 of its 11 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a short note recognizing a source of information or of a quoted passage
“the student's essay failed to list several important citations”
an indicator that orients you generally
“it is used as a reference for comparing the heating and the electrical energy involved”
a book to which you can refer for authoritative facts
“he contributed articles to the basic reference work on that topic”
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”
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”
the act of referring or consulting
“reference to an encyclopedia produced the answer”
a publication (or a passage from a publication) that is referred to
“he carried an armful of references back to his desk”
(computer science) the code that identifies where a piece of information is stored
the relation between a word or phrase and the object or idea it refers to
“he argued that reference is a consequence of conditioned reflexes”
Synonyms, antonyms and the broader and narrower relations for reference come from Princeton University’s WordNet. Full sources and licences.