Typically the answer to that question is FICTION is the opposite of FACT.
But what constitutes either fact or fiction? Fact must be a proven truth, a truism or established natural law, not just a theory. A theory is a conditional or hypothetical fact, which is itself fiction based on the best currently known assumptions. So, if you include THEORIES (Relativity, Atomic, Evolution, Big Bang, various economic theories, etc.) as a type of fact, then FICTION can't be the precise opposite.
Even if you agree that FACTS must be TRUE, a better antonym, in my thinking, would be FALLACY. This is because FICTIONS may be pure fabrications for the sake of fantasy, or they may contain a substantial amount of facts; as in historical fiction. However, all fiction contains FALLACIES. The fallacies are either there by design to fill-out a story to make it more interesting, for instance to supply historical or logical gaps, fictional dialogue, missing pieces of information, or a second fabricated fictional side story line, etcetera, or they are there accidently because the source material is faulty.
If FACTS MUST be 100% known TRUE and PROVABLE to all parties without any degree of FAITH in order to count as FACT, then you are left only with MATHEMATICAL CONSTRUCTS and DESCRIPTORS, and other self-identified scientific terms as in a well written technical manuals that describe the inventor's intentions, which are ultimately mathematically based. In other words, most mathematics can be and is fact because we can legitimately say so; we have defined them and assigned them the status of fact in a way that is ALWAYS TRUE and PROVABLE. This is legitimate because we can define such facts. This is why MATH is called the ONLY PURE SCIENCE. (Hint: Even in math we have not yet proved EVERYTHING. We just "know" that given enough time and intellect we could prove all our mathematical (ouch) "theories.")
Therefore, if in your question, FACT is taken in that sense where MATH ALONE is FACT, then the opposite of FACT is neither FALLACY nor FICTION, but anything, all things, which are not pure math. I suspect, however, that you are looking for a less esoteric, philosophical, or even less scientific answer. I theorize that rather, you were seeking more of a practical linguistic one. So, for the sake of pragmatics, define FACT then take your choice: the opposite is either fallacy or fiction-or both (or neither) LOL!
Of course, you could go mystical / spiritual and ask, If FACT is TRUTH, what is TRUTH? Then you have Jesus answering that same question posed by the Roman Governor, Pontius Pilate, by saying, "I am the Way, the Truth, and the Life," therefore the opposite of TRUTH is not just a LIE, but "the Liar" and all the lies he represents. Think about it.
The opposite of reality is fantasy.
_____________
Fantasy describes a dream, which classically pertains to (a) thoughts suspended between: incubation, birth or death. When this thought is realized, it becomes reality.
Fantasy describes a possibility.
Reality may be a by product of fantasy, and arguably, without fantasy - reality would not come into being.
Does reality have a polar opposite?
Politics. No, but really... I'm going to take an over-the-top approach. Reality as a system is 'incomplete' in the same sense that arithmetic is 'incomplete'. This means that it is possible to make propositions that contain more information than all of the system's axioms combined. In other words, you can come up with theories or propositions that are unprovable within the confines of the system. I'm suggesting that "the opposite of reality" is such a proposition.
We could conclude then that "the opposite of reality" either does not exist, or that there is no way to prove or disprove its existence. Anything that could be said in answer to the question, including the basic responses "unreality" or "fiction", are in fact just part of "reality". To sum up, it's all good.
# Opinion # Fiction
The opposite of fact is fiction or an untrue statement.
fiction
The opposite of Fact-Based is Opinion-Based
The opposite of realistic (in appearance) could be abstract, or surrealistic.
The opposite of realistic (reasonable, practical) could be unrealistic, impractical, or infeasible.
The opposite of fact is fiction.
Fictional
Fiction
The comparative form of realistic is more realistic
That is called realism.
A book that is fiction, but can happen in real life is a realistic fiction book.
How realistic is the story?
Realistically, the girl drew a beautiful view.
The opposite of realistic (in appearance) could be abstract, or surrealistic. The opposite of realistic (reasonable, practical) could be unrealistic, impractical, or infeasible.
Realistic sculpture.
"Down to Earth" means realistic, practical, everyday. It is the opposite of "head in the clouds."
They're opposite signs. Virgo is more perfectionistic and realistic while Pisces is more casual and a dreamer.
No, Fauvism was the opposite of realism. It aimed to recreate the sensations of the artist and light through the juxtaposition of bright colors which had nothing to do with nature.
The term "abstract art" covers a wide variety of art. The general sense of the term is that it is the opposite of the concrete, or "realism". It is "not realistic" Answer 2: It does not have an identifiable subject.
Some antonyms (words with opposite meanings) to fantastic are: Plain, ordinary, standard, normal, mediocre, expected, indifferent, realistic, real, average, acceptable, familiar.
The comparative form of realistic is more realistic
realistic theatre demonstrate realistic subjects that can possibly happen to people
Probably realistic fiction.
These expectations are not very realistic.The book felt so realistic and real.
realistic stories it happened in real life and can happen in real life