What does ebbw mean in welsh?

"Ebbw" is not a Welsh word. It is likely you are thinking of the River Ebbw, which flows through the town of Ebbw Vale in south Wales.

The river's name is likely derived from the Welsh word "Ebw" which means "river" or "stream".

It's possible that the name "Ebbw" is a shortened or altered version of "Ebw" over time.