The name Un appears once in Numbers 16:1 as one of the men who joined Korah's rebellion against Moses and Aaron. He is identified as a son of Peleth, from the tribe of Reuben. The name may derive from a root meaning "strength" or possibly relate to aven (iniquity).
Korah's rebellion (Numbers 16) is one of the most dramatic judgment narratives in the entire Torah. Un, along with Dathan and Abiram, challenged the Levitical and Mosaic authority established by God, claiming that all the congregation was holy and Moses had no right to elevate himself above them. This challenge — though framed as an appeal to equality — was actually a rejection of God's appointed order. The earth opened and swallowed the rebels. The lesson: challenging God's ordained authority is not spiritual boldness but fatal presumption.