It's when there's something with so much vast quantities of amazing you have no other word to use! It's like when your eating a piece of beef jerky, or the feeling you get when you take a big poop, or when you have the satisfaction of punting a gnome, or the way you express yourself when you give yourself head. Amazinism can move mountains and make your penis bigger. It can heal the sick and cure the limp dick.
It's Brilliant! It's Far out! It can make you pee blood! It's Amazinism!
Jill: Hey baby do you like my dress?
Penis: It's AMAZINISM!