what is a 'trainer'

[Dell Dimensional]

I'm not 100 % sure but almost it's not the same thing, it's like a small cheating application you run before you start the game it's meant for, you don't shut it down when you play, then you can press certain keys (or combinations) hopefully to be seen in the trainer itself, to activate somthing in the game, like if you press 'E' all enemies becomes blind or if you press CTRL+F you get all weapons, you get the point I guess...

btw I'm from Sweden so I reserve myself for any eventual spelling error