The dictionary disagrees with you. It means to be completely absorbed in the thing. It’s typically used to mean feeling like you are really in the fiction of the thing you’re engaged with and/or so absorbed by it you don’t pay attention to the real world around you. So immersed in a horror movie you get scared, so immersed in a book you don’t hear someone talking to you, so immersed in a game…etc.
That’s not true at all. Certain mechanics are inherently more immersive than others. Fully realized and fully explorable 3D worlds are more immersive than side scrollers, as an example. First person is more immersive than third person. Anything that encourages you to focus on the fiction helps immersion; anything that pulls your focus away from the fiction hurts immersion.
Yep. Real-time games are more immersive because you as the player are using your reflexes to control your character, so you feel…in a very literal way…more connected to the character and more connected to what’s happening in the game, i.e. you’re more immersed in the game. Read up on immersion in video games. It’s one of dozens of topics video game companies spend real money researching. It’s fascinating. And no, it’s not shorthand for “I don’t like it.”