Importance listing?
 

I know that the first is primary, and that second is secondary, and that third is tertiary...

Does anyone know the rest of the list? Like... At least up to five or six?

What you seek are the "ordinal" numbers (as opposed to "cardinal" or "nominal"). And since our language is mostly derived from Latin, it would follow that our numbering system would get its names from Latin as well.

1st primus (primary)
2nd secundus (secondary)
3rd tertius (tertiary)
4th quartus (quartiary)
5th quintus (quintiary)
6th sextus (sextiary)

Although, I've rarely seen anything over "tertiary" used.

That's awesome! Thank you very much.

Good God JadziaDax, do you know everything?

Would it really be so bad if she did?

Geologically, we live in the Quaternary period, rather than Quartiary.

Uh-oh, we got a battle over intellect going on here...