Balaibalan (Ottoman Turkish: باليبلن, romanized: Bâleybelen[a]) is the oldest known constructed language.
Balaibalan may have been created by 14th century mystic Fazlallah Astarabadi, founder of Hurufism, or collectively by his followers in the 15th century,[3] or perhaps by Muhyî-i Gülşenî, born in Edirne, a member of the Gülşenî sufi order in Cairo; in any case, the elaboration of the language was a collective endeavour.
[1][4] The sole documentary attestation of Bâleybelen is a dictionary, copies of which are to be found in the Bibliothèque nationale de France in Paris and in the Princeton University Library.
Balaibalan is an a priori language, written with the Ottoman alphabet (Arabic script).
Much of the lexis appears wholly invented, but some words are borrowed from Arabic and the other source languages, and others can be traced back to words of the source languages in an indirect manner, via Sufi metaphor.