What is the meaning of Constructed_language?

Any languagewhether a human language, a programming language, or markup languagethat is not a natural language.

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.

Any language used by people, as opposed to less civilized means of communication, such as the socialization between animals.

Source: wiktionary.org