The word means different things to everyone as the umbrella term "autism" is all encompassing.
To me, autism equates to a quiet word that keeps to itself, likes doing the same things over and over again, cannot really do "normal" things, but doesn't really care either; harms no one unless they harm it, and ultimately, just wishes to be left alone. There's some pain when autism cannot handle the noise, and it might go and bang its head, cut itself, or pop a tranquilizer, but this is just in response to trying to do something that autism cannot do.
Your mileage will vary depending on how it affects you, or those around you.