The term referring to the mass of genetic material found in the nucleus is chromatin.

Here's a breakdown:

* Chromatin: This is the complex of DNA and proteins that make up chromosomes within the nucleus of eukaryotic cells. It's essentially the uncoiled form of DNA.

* Chromosomes: These are the condensed, highly organized structures of DNA that become visible during cell division.

So, chromatin is the fundamental material that forms chromosomes, and together they represent the entirety of a cell's genetic information.