Theists: What do you mean when you say that God is 'perfect'?

[Neo-Scholastic]

You suggest that his completeness consists in Him being essentially self sufficient in and of himself.  I think you're alluding to aseity here, and I would have to say that I think introducing this form of self-sufficiency as a form of completeness which might be described as a perfection is in some sense introducing a concept that is alien to our intuitions about perfection and so amounts to essentially redefining perfection to be something that it is not.  

I believe it's an archaic use of the word 'perfection'. Kind of like the way 'movement' is an archaic way of referring to change. So I do think you have a point in that referring to God as perfect now-a-days, given its contemporary meaning, drags in more concepts than it should. It does lead to confusion. That's part of what makes it so difficult to study Classical philosophy; I have to make sure that I am properly interpreting the nomenclature as it would have been understood back when it was written. That's also why I'm being a little circumspect about fully entering into this debate. I foresee the danger of talking past one another.

(Also, I misspoke. Divine Perfection is in Question 4, not 3. That's what happens when I don't have the text in front of me.)