Since, again, I ought to start by saying that I don't believe in a God of any kind anyway, then it's perhaps not too surprising that I can't quite define what a God I might be defending is like exactly.
The closest, I think, would be the following: as powerful, as good and as knowing as anything can be. I don't see that it's possible to be infinitely anything, since one can always invent cases that show that there ought to be limits to God's power. Examples including that seriously annoying "can God make a rock too heavy for him to lift?"; or more seriously "Can God give us free will while also ensuring that we always choose to do the right thing?" which would have been nice of him to manage.
What this boils down to really is that I think the words omniscient etc., are too woolly to be of any use without defining them more precisely. While a dictionary doesn't fuss over this (I have a Chambers too, and it sticks to omniscient = all-knowing) I think we should, and need to define the words more carefully. What consequences these have, I don't know exactly. I suspect that in the case particularly of omniscience I probably try to bind God far too tightly, and in doing so effectively turn him into a Scientist who has "finished Science".