constructed language

Wiktionary

1. n. linguistics A human language that has been consciously devised by an individual or a small group, as opposed to having naturally evolved as part of a culture like a natural language.
2. n. Any language, whether a human language, a programming language or markup language, that is not a natural language.
3. n. linguistics, archaic Any language used by people, as opposed to less civilized means of communication, such as the socialization between animals.