[CarlRJ]

For a humorous taste of a limited language, without venturing outside of English, Randall Munroe (the XKCD guy) has a book called, "Thing Explainer", that's a sort of encyclopedia written using only the 1,000 most common words in English.

[natmaka]

AFAIK the first edition of the Longman Dictionary of Contemporary English (LDOCE), which "uses 2000 common words in the definitions to make understanding easy", was published in 1978.

https://www.ldoceonline.com/about.html