Problem: when doing a search on Google, the results will be in the language set for your Google account, or if you are not logged in, for this specific browser. See: https://www.google.com/preferences#languages

There is not query parameter you can use with Google to return results in a particular language, just once. Solutions include:

• changing search language each time: No!
• setting up several Google accounts: No! (lol thx google https://productforums.google.com/forum/#!msg/websearch/GE35k2IXj3g/c5chRpZVVFcJ)
• using several browsers: No!
• using hl or lr URL parameters (https://www.verot.net/google_language.htm?lang=en-GB)
  • &hl=xx: Google interface and results in xx language
  • &lr=lang_xx: Google results in xx language

A bit tedious, you can use custom search engines in your browser (https://webapps.stackexchange.com/questions/27918/how-can-i-make-google-do-one-shot-searches-in-a-specific-language-only) On Google Chrome, one way to do that is to add a search engine with the following URL: https://www.google.fr/search?q=%s&hl=xx, and invoke it using its keyword. On Firefox, it is sadly more complicated to create a custom search engine:

• create search engine: https://stackoverflow.com/questions/9963256/adding-a-custom-search-engine-to-firefox
• create a "bookmark" to search engine (with URL https://www.google.com/webhp?&hl=xx)

Problems:

• Setting up for several languages is tedious
• What about when searching results in multiple languages?

A simpler solution would be an browser extension that would allow the use of a parameter in the search box to set the language of the results for this query. Example:

diderot --lang=fr # returns results in french
shakespeare --lang=en,de  # returns results in english and german

Is this only possible in browsers (at least in sufficiently sane way)? Further investigation is needed.