Yes, I believe that was my point. "Error" is not the same thing as "sin". "Infallible" means without error, and, applied to the Pope, it specifically means his ability to teach without error under Divine protection.
I fail to see what you are arguing about. Yes: sometimes words have specific technical meanings. "Mouse" is either a computer peripheral, or a small rodent which is often a pest. Do you call the thing next your keyboard a "pointing peripheral device" because you don't want to stray from the commonly accepted definition of a word?
But, as I point out, the commonly accepted definition of "infallible" is "without error". That's what I said it was.
Are you just trying to be obtuse?
No, I'm trying to get you to be specific.
The "what about it" I went into in post #7. I'll admit to plenty of ignorance, but surely, Vatican II was ex-cathedra, no?
The term ex cathedra is usually reserved to an infallible Papal pronouncement. Vatican II was an ecumenical council, which is also capable of teaching infallibly.
So the question is, did Vatican II infallibly teach something concerning faith or morals which contradicted something which had been infallibly taught before?
The answer is no, it didn't. There are some Catholic traditionalists who argue that Vatican II contradicted early Papal pronouncements concerning religious liberty. However, the case is weak for arguing either that Vatican II's pronouncement or the earlier Papal documents are infallibly defined teachings. (Not everything is infallible; not everything needs to be.) And, the case is even weak for arguing that a contradiction exists at all.
So, one more time: what, exactly, do you think Vatican II changed that contradicted something previously defined infallibly?