"There’s the silver lining I’ve been looking for," she whispered, and then she was kissing him as she had never kissed him before, and Harry was kissing her back, and it was blissful oblivion better than firewhisky; she was the only real thing in the world, Ginny, the feel of her, one hand at her back and one in her long, sweet-smelling hair— The door banged open behind them and they jumped apart.
…toward them, sucking their way closer to Harry’s despair, which was like a promise of a feast… He saw Ron’s silver terrier burst into the air, flicker feebly, and expire; he saw Hermione’s otter twist in midair and fade, and his own wand trembled in his hand, and he almost welcomed the oncoming oblivion, the promise of nothing, of no feeling… And then a silver hare, a boar, and fox soared past Harry, Ron, and Hermione’s heads: the dementors fell back before the creatures’ approach.
There are no more uses of "oblivion" in the book.
Show samples from other sources
And if he kept his eye peeled quickly he would see himself, an instant before oblivion,
Ray Bradbury -- Fahrenheit 451
The ache inside Thomas was deep and gnawing, and he tried to sink further into oblivion.