I'm writing a book and I want to write a chapter where the antagonist beats the protagonist and, well, I want to imply that he rapes her without really writing details about him raping her or writing anything too explicit. How might I do that? What vocabulary should I use for this?
I want to imply that he rapes her without really writing details about him raping her or writing anything too explicit
Don't write the scene. Just write the lead up to it, and then afterwards. Each character should have a very different "opinion" of the event, he-said-she-said, so the reader will have to work it out, and nothing is worse than their imagination.
Like a monster movie, never show the whole monster. Just show bits and glimpses half hidden in the dark.
Talk to someone who has been raped, and ask them what it is that they did afterwards / what went through their mind / what the scene was like.
There are various voices your narrative can take - pain, confusion, horror, even humor. All can be utilized well here, but for all of them I would advise making sure that they do not come off as fabricated or fake. This may seem flippant (not my intent), but there isn't a correct rape vocabulary. This is about understanding it as best you can, and fitting it to the narrative's voice.
I'd have her use language like "She couldn't focus on what was happening. She couldn't focus on the pain, the thrusting pain, the violation. The guilt. Not that. It was easier to think about the ceramic floor tiles, the ones that she had chosen when her cousin was in town. The man had said this line picked up the color of the paint, and they had, he'd been right about that. But they were so hard, and cold, and were supposed to be stain resistant but she wasn't sure. The grout wasn't. The coffee she'd spilled that morning, that was probably right underneath her. She thought about that. She needed a new bottle of bleach."
Of course, more than this, so that it does not come off as dismissive. But the idea of dissociation can work to your benefit.