Alien languages, i.e., languages of extraterrestrial beings, are a hypothetical subject since none have been encountered so far. The research in these hypothetical languages is variously called exolinguistics, xenolinguistics or astrolinguistics. The question of what form alien languages might take and the possibility for humans to recognize and translate them has been part of the linguistics and language studies courses, e.g., at the Bowling Green State University (2001).
Noam Chomsky (1983), basing on his theory of the existence of a genetically-predetermined universal grammar of human languages, holds that it would be impossible for a human to naturally learn an alien language because it would most probably violate the universal grammar inborn in humans. Humans would have to study an alien language by the slow way of discovery, the same way as scientists do research in, say, physics.
Linguist Keren Rice posits that basic communication between humans and aliens should be possible, unless "the things that we think are common to languages—situating in time [and] space, talking about participants, etc.—are so radically different that the human language provides no starting point for it." 
McGill University Linguistics Professor, Jessica Coon was consulted for the linguistic aspect of the 2016 film Arrival. While acknowledging that the language used in the film was art, she states that film is a fairly accurate portrayal of the approach human linguists would use in trying to understand an alien language.
- An early use of the term "xenolinguistics" in science fiction occurred in 1986, in the novel "Triad" by Sheila Finch (Finch, Sheila (1986). Triad. New York: Spectra. ISBN 9780553257922. New edition: Finch, Sheila (2012). Triad. Rockville, Maryland: Wildside Press. ISBN 9781434447913..
- Daniels, Peter T. "Aliens And Linguists (Book Review)." Library Journal 105.13 (1980): 1516. Academic Search Premier. Web. 7 June 2012.
- Schirber, Michael. "Use Grammar To Decipher Alien Tongues." New Scientist 199.2678 (2008): 12. Academic Search Premier. Web. 7 June 2012.
- Course notes by assistant professor Sheri Wells-Jensen, Bowling Green State University (retrieved June 19, 2017)
- "Things No Amount of Learning Can Teach", Noam Chomsky interviewed by John Gliedman, Omni, 6:11, November 1983 (retrieved June 19, 2017)
- "Alien Interpreters: How Linguists Would Talk to Extraterrestrials". Scientific American. Retrieved 2018-04-09.
- "'Arrival' nails how humans might actually talk to aliens, a linguist says". Business Insider. Retrieved 2018-01-19.