A state of mind in which one willingly ignores evidence that things are not what they seem; in which one willingly accepts certain premises which might normally be resisted.
For example, you go to see a movie like Star Wars and become involved in the story. You are enjoying the film, and are thrilled by the loud explosions when tie fighters are blown up by our heroes. Your suspension of disbelief, your vacation from judgement, allows you to experience the sounds of outer space combat as an enjoyable part of the story, even though there would be no such sounds if you were really in outer space, where noise would not propogate as it does in earth's atmosphere.