Ceniza (Spanish for “ashes”) comes from the Latin cinis, meaning the same.
From the Latin root cinis, we get the English… cinder as well as incinerate. That makes sense: these are either the cause or the result of the process that causes ashes!
The most interesting part is.… this also explains why the Cinderella fairy tale, in Spanish, is called… Cenicienta!
We can see the c‑n root clearly in all these variations.