Onuist is the Pictish language and Old Welsh language counterpart of the Old Irish language name Aengus (also Óengus). Pictish is a term used for the Extinct language or languages thought to have been spoken by the Picts, the people of northern and central Scotland Old Welsh (Hen Gymraeg is the label attached to the Welsh language from the time it developed from the Brythonic language generally thought to be in the period Old Irish is the name given to the oldest form of the Irish language, or rather the Goidelic languages, for which extensive written texts are possessed It sometimes appears as Ungus or Hungus.
It usually refers to one of two Pictish kings named Onuist son of Uurguist (OIr Óengus mac Fergusso or Óengus mac Fergusa; anglicisation Angus son of Fergus):