constructed language

noun3

1. •
   Any language—whether a human language, a programming language, or markup language—that is not a natural language.

   • So if the constructed language is machine code, that is very fine, because the syntax (the grammar) is very simple and the meaning of each instruction can be verified [...] — 1972
2. •
   A human language that has been consciously devised by an individual or a group, as opposed to having naturally evolved as part of a culture like a natural language.
3. •
   (no longer used) Any language used by people, as opposed to less civilized means of communication, such as the socialization between animals.