A completely, utterly, above-all amazing or astonishing thing, event or person. A word in which to describe something that is out of this world.
Can also be used to finally cover up the speechlessness of joy-filled shock.
(AKA: what one would say if they were completely speechless/overcome with joy or dumbfoundedness).
Jose: "I just replaced all the water in my water bed with jello!"
Diego: "That is so cosmagorical, man!"