A living language can change, sometime startlingly rapidly. In fiction it's employed to suggest cultural change, or a character's status as FishOutOfTemporalWater.

Compare EternalEnglish.
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!!Examples:

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[[folder: Anime & Manga ]]

* In the ''LightNovel/CrestOfTheStars'' novels, the language of Jinto's home planet of Martine is said to be descended from English but when they hunt down someone who actually does speak English Jinto can't understand a word of it. The Japanese = Baronh and English = Martine in the anime is presumably a TranslationConvention.

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[[folder: Film ]]

* In ''Film/{{Idiocracy}}'', the massive proliferation of stupidity in American society has resulted in a corresponding degradation of the English language. The protagonist, our FishOutOfTemporalWater, is regarded as talking "like a fag" (presumably meaning "overly formal") when speaking normal 21st century English.

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[[folder: Literature ]]

* In ''Literature/GulliversTravels'', it is stated that most [[AgeWithoutYouth Struldbrugs]] are incapable of speaking more than a few words to those around them due to that trope. It is unclear how much that trope affects the written language, since there they suffer another problem - they can't remember what they just read.
* A major theme in ''Literature/RiddleyWalker''. It's post-apocalyptic fiction, and the book is just barely understandable, if you read it carefully and sound it out phonetically. Their conflation of various words of today's English (notably "Adam" and "atom") lead to much of the background, folklore, and plot.
* ''Literature/ACanticleForLeibowitz.'' By the time the events of the novel take place, English had long splinted into various successor languages. And the only ones speaking it are in the Catholic Church.
* In MichaelCrichton's ''Literature/{{Timeline}}'', three characters who travel back in time to TheMiddleAges have to learn how the French of that time differs from modern French. Even the character who already knows the written language of 1357 has to learn how it's pronounced and inflected.
* Used Creator/IsaacAsimov in his Empire and Literature/{{Foundation}} series. ''Pebble in the Sky'' features a protagonist who inadvertently steps into the future, where his 20th century English is unintelligible to all except a few historical linguists. Even they struggle. In ''Foundation'', Asimov repeatedly refers to the standard Galactic tongue as evolving throughout out time, and isolated worlds tend to fall behind, resulting in [[YeOldeButcheredeEnglishe Ye Olde Butcherede Galacticke Standarde]]. The change, however, is noticeably slower than in real life - it takes about five centuries for a document to start sounding queer, and a historian states the difference between his language and today's English is not that radical - different pronunciation and a lot of obsolete words, but not that different in principle. However, an isolated planet had its language completely unchanged, because, apparently, its people depend on robots, and maintaining the same language (in a society with little personal interaction) is easier than changing the programming.
* In the ''Legacy Trilogy'' by William H Keith Jr (writing as Ian Douglass), due to relativistic travel, characters come back to Earth after many years away and find that they're unable to understand what people are saying or be understood themselves without special translation software.
* In ''Literature/TheForeverWar'', by the mid-21st century, pronouns have already begun to shift. Centuries later, 20th century English has become the Lingua Franca of the Force, since most of the military brass, having lived hundreds of years through relativistic travel, speak it.
* Becomes a major plot point in ''Literature/CourtshipRite'' when the inhabitants of the LostColony of Geta finally decode ancient documents, including a history of Earth, and learn, among other things, that their word for "God" used to mean "ship". Which puts a whole new perspective on the legend that the God in the sky that they can see every night brought them to Geta.
* In the "Mage Storms" trilogy in the ''HeraldsOfValdemar'' series, a minor plot point involves the Kaled'a'in clan, who are the only speakers of their language. They pride themselves on keeping it "pure" and unchanged over the millennia -- so naturally two native speakers are dismayed to find they cannot read a very important set of inscriptions in ancient Kaled'a'in.

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[[folder: Video Games ]]

* The 'lyrics' in ''{{Nier}}'''s soundtrack are written in futuristic versions of French, English, Japanese etc (and despite sounding like gibberish, you can actually tell which language they're been based upon), because the game itself takes place a few thousand years after the 2000s.
* [[TimeSkip 200 years pass]] between ''VideoGame/TheElderScrollsIVOblivion'' and ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]''. Though you can still understand the Imperial tongue perfectly, the names used by some ethnicities indicate that the language has evolved. Many Imperials now use Italian-like names instead of CanisLatinicus, and the Redguards are mainly a mix of Arabic and Moorish instead of the {{ghetto|Name}}-ish ones they had in ''Oblivion''.

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[[folder: Western Animation ]]

* The Business Men from ''WesternAnimation/AdventureTime'' have very bizarre grammar, but when one combines the WordOfGod statement that [[spoiler: the show takes place [[AfterTheEnd after a nuclear war wiped out most of humanity]]]] and the fact that they were implied to be [[HumanPopsicle Human Popsicles]] from the past, it becomes apparent that they are speaking contemporary English; the other characters just have TranslationConvention on their side. When Finn found the tribe of [[spoiler: Humans]] they're speaking a language that could hardly be recognized as English.
* In ''The Mézga Family'', a Hungarian cartoon from the 70s, the titular family, living in the 20th century, manages to contact a descendant called MZ/X, who lives in the 30th century. At first they don't understand a word he's saying, as MZ/X speaks "new Hungarian", which is just modern day Hungarian with EVERY word abbreviated to one syllable. Thankfully he has a telepathic helmet he can put on when he wants to talk to his ancestors from "the atomic dark age", as he calls them.

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[[folder: Real Life ]]

* The archaic Latin [[http://en.wikipedia.org/wiki/Carmen_Saliare chants of the Roman priesthood]] were indecipherable even to Cicero in the 1st century BCE. The only recognizable words are Ceres, Janus, and thunder. The [[http://en.wikipedia.org/wiki/Donation_of_constantine Donation of Constantine]] was recognized as a forgery when it used 8th century CE Latin words in a document supposedly written in the 4th century CE. See the wikipedia article on [[http://en.wikipedia.org/wiki/Latin Latin]] for a history on the different forms of the language.
* Similarly to the above, the Greek Language has shifted considerably from [[http://en.wikipedia.org/wiki/Ancient_Greek the time of Homer]]. Indeed the New Testament was translated several times in the past century because so few could comprehend the [[http://en.wikipedia.org/wiki/Koine_Greek late Hellenistic language]] most of the Gospels and Epistles were composed in.
** That said, for a speaker of Modern Greek, reading the late-Hellenistic Greek of the New Testament is more akin to a speaker of Modern English reading Chaucer than a speaker of Modern French reading Latin--it's archaic and difficult, but it can be done with liberal use of a dictionary. At that point, however, it's so difficult it's worth translating into the modern form.
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