I saw a video years ago in which the word "unreal" was used to describe a tennis legend (Roger Federer). Several tennis stars were invited to interview in the video. One of the tennis stars used the two words, "not real" instead of "unreal". I know that he tried to show his most sincere admiration for the other player. However, I then wondered, why not just use the word "unreal"? It is one word and in my opinion, "unreal" and "not real" can be used interchangeably, right? Or maybe there's something different between them that makes them not interchageable in this context.

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    They are not interchangeable. "Not real" means imaginary, and "unreal" means "hard to believe" or "rare". Roger Federer does exist, but his legendary status might be hard to understand. Commented Sep 23, 2022 at 15:14
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    "Not real" means doesn't exist (as it happens), and "unreal" means couldn't / shouldn't exist (because too unusual). Commented Sep 23, 2022 at 15:17
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    While this isn’t the context here, real also has a technical meaning in mathematics “related to the set of real numbers” or “the real part of a complex number.” In this context, “not real” means the opposite, and we do not use “unreal” in mathematics, at least not in this way.
    – Davislor
    Commented Sep 24, 2022 at 13:30
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    @Davislor to add, in this mathematical context only, it would be appropriate to say "these numbers are non-real."
    – Drake P
    Commented Sep 24, 2022 at 18:21

7 Answers 7


"Unreal" is an extreme adjective that means "fantastic", "incredible", "unbelievable", etc. All these words can be used figuratively to mean "really good". "Unreal" literally means it's so good it must not be real. "Fantastic" literally means it's just a fantasy, something imagined. "Incredible" and "unbelievable" both literally mean it's so good nobody can believe it. But they're all used figuratively, and used so often that they no longer have the literal meaning at all.

"Not real", on the other hand, is never used figuratively. It always means the opposite of "real".

So when this tennis star described Federer as "not real" (I'm giving him the benefit of the doubt it was intentional), he was carefully choosing not to use a normal adjective that means "really good". Rather, he was using the normally literal expression "not real" in a figurative way to say that it's actually difficult for him to believe anyone can be that good at tennis.

For what it's worth, this process is where the "really good" meanings of all the words I mentioned come from. Initially, they were literal words, and when used figuratively, they were so powerful that people started using them all the time to mean "really good", and they lost both their literal meaning and their power. Whichever tennis star said this is clever with words.

  • "he was using the normally literal expression "not real" in a figurative way". Wouldn't "surreal" have been more appropriate in that case? That is, something that one knows is real but find almost impossible to believe. (Note that I'm not criticising Federer's choice of words.) Commented Sep 24, 2022 at 14:09
  • @RayButterworth Using "surreal" would be using a word in its literal sense. Whoever said this (it was some other star, not Federer) used "not real" figuratively because it's almost never used figuratively, so it had more impact.
    – gotube
    Commented Sep 24, 2022 at 16:00
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    "Whichever tennis star said this is clever with words" - possibly, or it's a non-native speaker who just meant "unreal".
    – NotThatGuy
    Commented Sep 25, 2022 at 0:49
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    Imagine the uninspired results of programming a game with the "Not Real Engine"... "Bruh, these graphics look cheap and don't resemble real life at all." "Well, yeah. It's just a computer program. It's not real. In fact, the game engine I used is called..." Whereas "Unreal Engine" invokes a different connotation.
    – Mentalist
    Commented Sep 26, 2022 at 4:58
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    @vaterherrn Better yet! I'm Spanish and I can confirm that we do use no (es) real in a figurative "unreal" sense as well as the more literal "not real" sense. The actual Spanish word for "unreal" would be irreal, but that's a rather uncommon word, found mostly in literary works, not in casual conversation. In other words, irreal in Spanish has not yet lost that "powerful" meaning that gotube alluded to, so we still lean to using no es real ("not real") instead. Which means a Spanish speaker should translate fig. "no real" as lit. "unreal" and lit. "irreal" as fig. "not real" 😐
    – walen
    Commented Sep 28, 2022 at 10:26

As a more general answer than those that have been posted so far, note that negation of a word can have more than one meaning. A very common case is that the negation can mean the absence of the thing, or the presence of its opposite. This is certainly true in English, and I’m sure there are bound to be similar phenomena in other languages.

As such, English frequently has multiple negated forms that seem alike, but take on specific meanings.

  • Amoral means “without moral judgement”, but immoral means “judged as morally bad”.
  • Careless means “not taking the expected amount of care”, but carefree means “not expected to take care”.
  • And my favourite ever since I mixed them up as a kid, worthless means “having zero value”, but priceless means “having a value too great to number”!

Not real and unreal are not so different as some of these, and there are some examples where either could be used (“it doesn’t seem real” versus “it seems unreal”) with little or no difference in meaning. There are other cases, probably the majority, where one or the other must be used to be correct.

Not real could be defined as the absence of reality, or truth, or genuineness. It’s generally a bad thing, because “real” is so often a good thing. (Where “real” takes on some specialised meaning, like in mathematics, it’s simply neutral. Though I’m sure many maths students would say numbers that are not real are a bad thing…)

Unreal could be defined as the presence of things that are not part of reality, as in dreams or fantasies. It can be a good or a bad thing, depending on the situation.

And finally, that means that the tennis player in question really ought to have described Federer as unreal, instead of not real—he exists, but his skills may seem like the stuff of fantasy!

  • +1 Fantastic that you noted "unreal" is not actually a negation. It is a positive adjective denotes the presence of something not real rather than the absence of realness.
    – gotube
    Commented Sep 24, 2022 at 16:06

Somtimes the word "unreal" and the phrase "not real" are interchangeable. Other times, they are not.

Ar times, people are sarcastic. At other times, people are serious. People use the word "unreal" more often when speaking sarcastically than they use the word "unreal" when being serious.

The word "Unreal" can mean the same thing as the phrase "factually true, but surprising".

For example, someone might write, "it is unreal that you did well on the last geography exam, but did poorly in chemistry".

  • Can you give an example sentence where "unreal" and "not real" are interchangeable without changing the meaning?
    – gotube
    Commented Sep 24, 2022 at 4:39

“Not real” and “unreal” have the same formal meaning of “imaginary” or “non-existent.”

However, “not real” and “unreal” have been adopted to mean “extraordinarily good” in popular American English.

I cannot agree with the comments that imply a distinction in meaning between “not real” and “unreal.” I do agree that people whose English is so impoverished as to believe that “not real” is a useful synonym for “extraordinarily good” may be unaware that the word “unreal” even exists. Because of that, it may be true that even good speakers reserve “not real” for figurative speech.

Personally, I’d just avoid the now trite use of “not real” to mean “far out of the ordinary.”


The word "unreal" is an adjective and somtimes precedes nouns.

The phrase "not real" does not precede nouns. For example, it is incorrect to talk about the "not real house" or talk about the "not real chair".

To fix this, we can change "not" to "non". The phrase "non-real" is almost the same in meaning and usage as the adjective "unreal".

"not" and "non" are subtely different.

"not real" must be preceded by the word "is", "are", or another conjugation of "to be".

You can use the phrases "is unreal" and "are unreal", but you are not required to so so.

Sometimes "unreal" is preceded by a word which is not a conjugation of "be".

Some examples of these words and phrases are shown below:

  • The unreal sheep danced in Joe's mind as he fell asleep (Correct)
  • The non-real sheep danced in Joe's mind as he fell asleep. (Correct)
  • The not real sheep danced in Joe's mind as he fell asleep. (In-correct)
  • The sheep dancing in Joe's mind were not real (correct)
  • The sheep dancing in Joe's mind as he fell asleep were unreal (correct)

tl;dr The terms "not real" and "non-real" are basically equivalent, and they both imply a lack of being real. By contrast, "unreal" usually refers to something that seemed real, but then that realness was somehow reversed. Usually "unreal" applies to situations where an event that seemed real was so extreme that someone questions if it actually happened.

Some folks also use terms like "unreal" hyperbolically, where the term isn't meant literally but rather as an exaggeration. In such scenarios, "unreal" might refer to something extreme, even if it didn't actually challenge their sense of reality.

"Not" and "non-" are logical negations; "un-" is for reversal.

In English:

  • the prefix "non-" implies a logical-negative;

  • the prefix "un-" implies reversal.

The qualifier "not" is more like the prefix "non-" than "un-".

For example, consider the difference been:

  • not doing, where the doing simply didn't happen;

  • undoing, where a doing was reversed.

Regarding the question:

  • If something is "not real" or "non-real", then it isn't real.

  • If something is "unreal", then it had a quality of realness, but that realness got reversed.

For example:

  • Fire-breathing dragons aren't real, so they're "not real" or "non-real".

  • But if someone sees a fire-breathing dragon, then they might momentarily accept its realness (because they just saw it), but then their inner scrutiny might object; for example, they might suspect some sort of trick, optical illusion, delusion, dream, etc.. So in their mind, the dragon was real in a way, but then that realness was contested (even if by their own skepticism), making it seem "unreal".

In general, the term "unreal" tends to be used in scenarios like that, where:

  1. something is accepted (or at least suspected) to be real;

  2. but, for whatever reason, that sense of realness is undone (even if partially), making it "unreal".

In practice, "unreal" usually refers to things that people (mostly) believe, but are so extreme that they struggle to fully accept it as reality. For example:

  1. Electric-lightbulbs may've seemed unreal to some folks shortly after they were invented.

  2. If a runner beats the world-record for speed by a significant margin, beyond what one expected could be done, then the runner's performance might seem unreal.

  3. Someone who's surprised with a huge gift might find the experience unreal.

Then when used hyperbolically (non-literally):

  1. If a runner beats the world-record for speed by just a little bit, then a loose speaker might exaggeratingly refer to it as "unreal".

Note: On extended uses of "un-".

Sometimes "un-" might be used abstractly or loosely.

For example, consider a new door that's just been installed and isn't locked. Strictly speaking, such a door can't be "unlocked" because it was never locked. That said, folks might still say that it's unlocked because:

  1. Abstractly: They're speaking of the physical-door as an instance of an abstract-door, where the abstract-door can be considered to have been previously locked.

  2. Idiomatically: Folks talk about "unlocking" doors a lot, so the term "unlocked" might be preferred on an idiomatic basis over a more precise term like "not locked" or "non-locked".

For another example:

  1. Not announced beforehand.

"unannounced", Wiktionary.

Here, a dictionary defines "unannounced" as though "un-" were a negative. This is a simplification – but one that might lead to confusion – so let's examine it.

First, a more robust definition might be more like:

  1. Having reversed a presumed announcement.

For example, say you're talking to your friend and they step away for a moment to use the bathroom. When they come back, it would be incorrect to say that they showed up "unannounced" – because merely being "not announced beforehand" isn't enough to be "unannounced".

Point being that, even if "un-"-words are sometimes described as being negations in a dictionary, usually they're better understood as reversals than negations.

Note: On extended uses of "unreal".

The term "unreal" has an extended usage as an exaggeration (hyperbole).

This is, even if something doesn't actually make someone question its realness, a loose speaker might call it "unreal" anyway.

This usually isn't good English, but still a potential usage to maybe be aware of.

  • I don’t agree that “un-” should always mean reversal rather than mere absence—I think that’s more true of “dis-” (e.g. “disconnected” vs “unconnected”)—but where it contrasts with “not”, this is generally going to be the case, so it’s a good rule of thumb. Commented Sep 25, 2022 at 4:40

Although it’s a different context than this quotation, one domain where we cannot use not real and unreal interchangeably is mathematics. There, real has a technical meaning, “related to the set of real numbers,” or “the part of an extended number system that consists of real numbers.” The opposite of this is not real, or non-real, and the non-real part of a complex number is imaginary, but we cannot say unreal in this context.

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