This is the article about constructed languages. For other uses of the term "a priori," see a priori

A priori

A priori is Latin for "from the former" or "from before", and may refer to:* A priori knowledge, justification or arguments. See a priori and a posteriori.* A priori , a type of constructed language...

.

An a priori language is any constructed language

Constructed language

A planned or constructed language—known colloquially as a conlang—is a language whose phonology, grammar, and/or vocabulary has been consciously devised by an individual or group, instead of having evolved naturally...

 whose vocabulary

Vocabulary

A person's vocabulary is the set of words within a language that are familiar to that person. A vocabulary usually develops with age, and serves as a useful and fundamental tool for communication and acquiring knowledge...

 is not based on existing languages, unlike a posteriori

A posteriori (languages)

An "a posteriori language" , according to Louis Couturat, is any constructed language whose elements are borrowed or based on existing languages, as opposed to the a priori languages....

 constructed languages. Examples of a priori languages include Ro, Solresol

Solresol

Solresol is an artificial language devised by François Sudre, beginning in 1827. He published his major book on it, Langue musicale universelle, in 1866, though he had already been publicizing it for some years...

, Mirad

Mirad

Mirad is an artificially-constructed auxiliary language developed and published by Paris-based author Noubar Agopoff as a serious medium for easy and logical international communication. Mirad is categorized by constructed language aficionados as philosophical because its vocabulary is mapped...

, Klingon

Klingon language

The Klingon language is the constructed language spoken by the fictional Klingons in the Star Trek universe....

, and Na'vi

Na'vi language

The Na’vi language is the constructed language of the Na’vi, the sapient humanoid indigenous inhabitants of the fictional moon Pandora in the 2009 film Avatar. It was created by Paul Frommer, a professor at the Marshall School of Business with a doctorate in linguistics...

. By contrast, a posteriori languages are ones whose vocabulary is based on existing languages, either as a variation of one language (e.g., Latino sine flexione

Latino sine Flexione

Latino sine flexione , or Peano’s Interlingua , is an international auxiliary language invented by the Italian mathematician Giuseppe Peano in 1903. It is a simplified version of Latin, and retains its vocabulary...

) or as a mixture of various languages.

Some a priori languages are designed to be international auxiliary language

International auxiliary language

An international auxiliary language or interlanguage is a language meant for communication between people from different nations who do not share a common native language...

s that remove what could be considered an unfair learning advantage for native speakers of a source language that would otherwise exist for a posteriori languages. Some a priori languages try to categorize their vocabulary, either to express an underlying philosophy or to make it easier to recognize new vocabulary. These are also known as philosophical

Philosophical language

A philosophical language is any constructed language that is constructed from first principles, like a logical language, but may entail a strong claim of absolute perfection or transcendent or even mystical truth rather than satisfaction of pragmatic goals...

 or taxonomic languages.