If you are engrossed in something, it has your whole mind. You are reading, watching, talking, or working, and the rest of the world has gone quiet. This is the form students meet most often — not the verb, but this state of being inside the thing. We almost always say engrossed in a book, a conversation, a game, a film. It is a little more written than spoken, but people do say it, and it is kind: it means the thing was worth disappearing into. It does not mean you are disgusted, even though gross in slang means that. Though actually, the older “written in large letters / taken in bulk” history of engross is still sitting under this word; in modern talk, though, you can treat engrossed as simply “so interested you notice nothing else.”