1) Infinitely sharp; possessing an edge (or tip) of zero thickness.
2) Tending, or possessing a tendency, to decapitate. (slang)
-= Usage and Etymology =-
In RPGs (role-playing games, such as Dungeons & Dragons and the Final Fantasy series), "vorpal" is an adjective describing and referring to a bladed (slashing) weapon that has been magically enchanted in order to imbue it with an edge that is infinitely sharp (or, significantly rarer, a similarly-imbued pointed (stabbing) weapon with an infinitely sharp tip). The result of a vorpal enchantment, which is achieved foremost through the casting of a magic spell by a sufficiently powerful mage (a wizard or enchanter, for example), is the melding of the actual edge of the (almost always) metal blade with the addition of a new, extended edge, which is not only composed of a substance of a magical and nearly impervious nature, but, as the outer limit of the new magical edge is approached, decreases in thickness until the two sides meet at what is literally a mathematical lin...
2. A specific enchantment upon a magical sword that, on a crit, severs the head of its victim automatically.
2. My vorpal longsword +2 made quick work of those Amnizu enforcers.
"The vorpal blade went snicker-snack!"
(Lewis Carroll, Jabberwocky)