The Khitan language (also known as Liao and Kitan (ISO 639-3); Chinese: 契丹語) is a now-extinct language once spoken by the Khitan people (388–1243AD). Khitan is generally deemed to be genetically linked to the Mongolic languages. It was written using two mutually exclusive writing systems known as the Khitan large script and the Khitan small script. The language was the official language of the Liao Dynasty (907–1125) and Kara-Khitan Khanate (1124–1218). Janhunen states "A better term for Khitan than Mongolic would be Para-Mongolic, implying that it was probably a language collateral to the ancestor of all the Mongolic languages." Presently the theory of the Mongolic, rather than Tungusic, affiliation of Khitan is more and more commonly accepted by both eastern and western scholars.
There are several closed systems of Khitan lexical items for which systematic information is available. The following is a list of words in these closed systems that are similar to Mongolic. Mongolian equivalents are given after the English translation:
Franks, H. (1976): "Two Chinese-Khitan Macaronic Poems." In: Heissig, W.-Krueger, J. R.-Oinas, F. J.-Schütz, E. (eds): Tradata Altaica. Wiesbaden, Otto Harrassowitz.
Kane, Daniel (1989). The Sino-Jurchen Vocabulary of the Bureau of Interpreters. Uralic and Altaic Series, Vol. 153. Bloomington, Indiana: Indiana University, Research Institute for Inner Asian Studies. ISBN978-0-933070-23-3.