This is one of those words (like Klenex) that is actually a brand reference but has been around (and used) so much that it is the standard name for everything of the type. To be more accurate, what most people call a frisbee is in general a "disc". The "Frisbee" is made by the company Wham-o... and is not known among Ultimate enthusiasts as a very good disc... it is better than nothing any day, but not good for games.
"You want to use a Frisbee? Man...go get the good disc."
A frisbee throw mainly used among Ultimate enthusiasts. It consists of an upsidedown forehand throw above the head that is meant to fall quickly. It is and unstable throw and not recommended for days with adverse weather conditions.