If you have 3 books you have a trilogy.  If you have 12, what is it called?  All I could think of is a dodecology

That depends on the series.

 

If it's realy bad:  Firestarters

If it's just okay:  Way too many

If it's good:      Pushin' it

If it's realy good: Just right

If it's WoT:        Leaving too much to be desired

Shelf Hog

I always thought anything with more then 3 books was just called a series. But I might be wrong.

4 books is a Quartet.

5 books is a Quintet.

Any more and I believe it is just called a series. :)

 

septet, ocho-et? dodecet. :P ::)