title_body: How do you call a "stillborn language"? And by "stillborn", I mean a dead language that never really lived to begin with: a modernized version of an archaic language frozen in time, or an all-out archaic language (with archaic grammar and vocabulary), but with modernized pronunciations (and all the vowel shifts and consonant shifts applied). Like Classical Latin, which was probably never spoken in daily life (in contrast with Vulgar Latin).
  
  Or just simply a language that is based off an actual natural language, but highly stylized and artificial, having had diglossia with its parent-language since the start, never having been an actual spoken language at any point in history.
upvoted_answer: You're describing a couple different and not totally related things with different terminology used for each: 
  
  
  Classical Latin is an example of a literary language, a language used not really in speech but used to communicate through writing.
  Modern Standard Arabic, one of those artificial languages based off of a natural one but not really being a spoken language. It's very frequently affected by diglossia, and not really used in natural settings. It's usually referred to as simply a standardized lanuage, and also qualifies as a literary language.
  Hebrew as spoken in daily life in Israel would qualify as the first type you described, a modernized version of an old language that was resurrected after death. It would be referred to as a revived language.