I'm perplexed on coffee types. What is filter ground coffee? I bought a new coffee maker and it has a permanent filter and says to only use filter ground coffee.What exactly is filter ground coffee?
Filter ground coffee stands for roasted, then cracked to smaller pieces to be brewed easily coffee beans. The question is, how small and consistent you should crack them to pieces. This is important as it affects the extraction of the coffee, so your cup. You should crack all the coffee beans at the same desired size for a good cup of coffee.

Here's a previous discussion on a similar topic, but on espresso machines: 


What is the right coffee ground size for an espresso coffee machine?


And, what about the right size? It should be about 400 microns for a drip machine that uses filter size grounds. But, don't worry. Coffee shops know about these. All you need to do is just ask for it or read the labels. Here is a quick chart for all coffee brewing methods and ground sizes: