"Sanctimonious" and "sententious" are nearly synonymous adjectives. Their Latin roots show their slight difference: "sanctus" means "holy" and "sententiosus" means "full of meaning"--Parsons puts on an expression that looks holy (because he is in the presence of a telescreen) to make a brief statement that's excessively filled with pompous morality.
His froglike face grew calmer, and even took on a slightly sanctimonious expression. “Thought-crime is a dreadful thing, old man,” he said sententiously.
inclined to anger or bad feelings with overtones of menace
He remembered a surly barber arriving to scrape his chin and crop his hair, and businesslike, unsympathetic men in white coats feeling his pulse, tapping his reflexes, turning up his eyelids, running harsh fingers over him in search of broken bones, and shooting needles into his arm to make him sleep.
"Abject" also means "most unfortunate or miserable" and "showing utter resignation or hopelessness"--all three definitions fit the example sentence. The second sentence, with its focus on free will, emphasizes that the Party wants subjects that are not abject. However, it uses the most abject ("of the most contemptible kind") methods of torture to make rebellious members surrender.
We are not content with negative obedience, nor even with the most abject submission. When finally you surrender to us, it must be of your own free will.
The list of qualities Winston will never be capable of having again ends fittingly with "integrity" because 1) it comes from the Latin root "integer" which means "whole, complete"; 2) it sets up the points about hollowness.
Never again will you be capable of love, or friendship, or joy of living, or laughter, or curiosity, or courage, or integrity. You will be hollow. We shall squeeze you empty, and then we shall fill you with ourselves.
"Luminous" also means "enlightened and intelligent" or "easily understood; lucid"--these definitions are a better fit for the example sentence, but the given definition emphasizes a contrast in mood between this moment and the one when all Winston saw was the "unvarying white light."
But there had been a moment—he did not know how long, thirty seconds, perhaps—of luminous certainty, when each new suggestion of O’Brien’s had filled up a patch of emptiness and become absolute truth, and when two and two could have been three as easily as five, if that were what was needed.
(philosophy) the philosophical theory that the self is all that you know to exist
I told you, Winston,” he said, “that metaphysics is not your strong point. The word you are trying to think of is solipsism. But you are mistaken. This is not solipsism. Collective solipsism, if you like. But that is a different thing; in fact, the opposite thing.
"Malleable" also means "easily influenced"--this should be the chosen definition when describing human nature. But O'Brien's point about creating human nature connects to its Latin root ("malleus" means "hammer"), which emphasizes the physical and emotional torture that Winston is undergoing.
But we create human nature. Men are infinitely malleable.
You have been kicked and flogged and insulted, you have screamed with pain, you have rolled on the floor in your own blood and vomit. You have whimpered for mercy, you have betrayed everybody and everything. Can you think of a single degradation that has not happened to you?
in a condition of biological rest or suspended animation
"Torpid" also means "slow and apathetic"--both definitions fit, but the chosen definition gives a stronger image of Winston's mood, which is the same whether he is awake or asleep. Compare with "lassitude" in the list for Part 1: Chapters 5-8--there, Winston panics at the lassitude that came with the possibility that his life might be over because he had been seen where he shouldn't have been; here, Winston knows his life is over and he cannot hide or fight.
From the moment when he was inside the Ministry of Love—and yes, even during those minutes when he and Julia had stood helpless while the iron voice from the telescreen told them what to do—he had grasped the frivolity, the shallowness of his attempt to set himself up against the power of the Party.