noun, prefix
Primarily a prefix or noun indicating something above, on top, or on the outer surface. Often used in compounds like うわ着 (overcoat) or うわべ (surface appearance).
うわ着を着て外に出た。
I put on an overcoat and went outside.
うわべだけの優しさでは信用できない。
I can't trust kindness that is only on the surface.
うえ is the more common reading for 'above/on top' and is used as a standalone noun and in many compounds. うわ is a less common prefix/noun reading used in specific compounds.
かみ means 'upper part' or 'upstream' and is used in words like 川上 (upstream). うわ is more about outer/top surface.
The reading うわ is a native Japanese prefix/noun related to the concept of 'upper' or 'surface'. It is cognate with うえ (上) and うわ (上) in compounds.