Aryan is an English wor derived from the Sanskrit "Ārya" meaning "noble" or "honorable". The Avestan cognate is "Airya" and the Old Persian equivalent is "Ariya". It is widely held to have been used as an ethnic self-designation of the Proto-Indo-Iranians. Since, in the 19th century, the Indo-Iranians were the most ancient known speakers of Indo-European languages, the word Aryan was adopted to refer not only to the Indo-Iranian people, but also to Indo-European speakers as a whole.