Question

When butter is heated melts, and when that melted butter cools and solidifies what is the process called?

Answer 1

I would call it fusion. It is the same process for cooling water into its solid form

Explanation:

The energy associated with freezing/melting water is called delta H of fusion `ΔH_"fusion"` Butter forming into a solid is freezing, but also called fusion. I guess you can call it either fusion or freezing.