Questions about languages, whether alien, fantasy, or human.
This tag is used for questions that are about language.
This includes alien languages that are commonly found in science-fiction (e.g. Vulcan), as well as fantasy languages (e.g. Elvish).
If your question relates to a human language (e.g. English, Spanish) then this tag is also appropriate. This side-steps any discussion about whether fully-realised languages (e.g. Klingon) is a "fictional language" or not.
If your question is more about a human language (e.g. German, French) than about science-fiction or fantasy, or not about a human language within the context of a specific sci-fi or fantasy setting, it might be more appropriate for the English Language and Usage site.