conlang

:  an invented language intended for human communication that has planned and cohesive phonological, grammatical, and syntactical systems Celebrated with a cult-following across the globe, Elvish, a constructed language or ‘conlang,’ is more than a code, like Pig Latin, … . Constructed languages like Elvish are real languages, made-up of thousands of words created by fantasy writers, linguists and fans, with real language rules. — John McWhorter