What is the normal melting point of a substance called?

Well, it is simply the $\text{normal melting point}$, as the name says on the label.
In older literature, you may see the melting point referred to as the $\text{fusion point}$. These are extensively tabulated for organic compounds. If you have an unknown organic material, and you want to identify it, the quickest means is to get an idea of what sort of compound it is, make a few derivatives, and compare the melting points to the known literature values. A couple of melting points confirms the identity of the organic material precisely and unambiguously. This is true today in spite of the vast array of instrumental means of analysis.