olemus
ISO 18587, 24620-1:
keel, mille päritolu ei ole teada, kuid mis areneb pidevalt,
kohati ainuomaselt ja on traditsiooniliselt kasutusel
inimsuhtluses
= language with its origin unknown, but continuously developing sometimes in idiosyncratic ways as is used conventionally for human communication

ISO 1087, 5127, 9241:
keel, mis on või oli aktiivselt kasutusel mingis inimkoosluses ja mille reeglid tulenevad peamiselt ta kasutamisest
= language which is or was in active use in a community of people, and the rules of which are mainly deduced from the usage

ISO 17100:
kirjalik, märgipõhine või suuline inimkeel
= written, signed, or spoken human language

ISO/IEC 2382:
keel, mille reeglid põhinevad käibival kasutamisel,
olemata spetsiifiliselt ette kirjutatud
= a language whose rules are based on current usage without being specifically prescribed

ISO 639-4:
inimsuhtluse keel, mis pole tehiskeel
= language for human communication that is not an artificial language

ISO/IEC 22989:
keel, mis on või oli aktiivselt kasutusel mingis inimkoosluses ja mille reeglid tulenevad ta kasutamisest
(i) loomulik keel on igasugune inimkeel, mida saab väljendada tekstis, kõnes, viipekeeles jne.
(ii) loomulik keel on igasugune inimkeel, näiteks inglise, hispaania, araabia, hiina, jaapani, mida tuleb eristada programmi- ja formaalkeeltest, nagu on Java, Fortran, C++, esimest järku predikaatloogika
= language that is or was in active use in a community of people and whose rules are deduced from usage
Note 1. Natural language is any human language, which can be expressed in text, speech, sign language, etc.
Note 2. Natural language is any human language, such as English, Spanish, Arabic, Chinese or Japanese, to be distinguished from programming and formal languages, such as Java, Fortran, C++ or First-Order Logic.

ülevaateid
https://en.wikipedia.org/wiki/Natural_language

https://en.wikipedia.org/wiki/Language_family

https://www.uni-due.de/SHE/SHE_Indo_European.htm

http://attempto.ifi.uzh.ch/site/pubs/papers/kuhn2013cl.pdf

https://en.wikipedia.org/wiki/List_of_languages_by_number_of_native_speakers

https://www.milestoneloc.com/natural-language-vs-constructed-language-vs-artificial-languages/

https://en.wikipedia.org/wiki/List_of_languages_by_total_number_of_speakers

http://www.sfs.uni-tuebingen.de/~gjaeger/lehre/ws1011/languagesOfTheWorld/folien1.pdf

https://lingua.edu/the-most-spoken-languages-in-the-world/

https://keywordtool.io/blog/most-spoken-languages-in-the-world/

vt ka
- loomuliku keele töötlus