Actually, almost all of the 'made-up' words in Jabber existed before Caroll used them. He just knew about them. I'm pretty sure that vorpal just meant wavy, but I'm not 100%. It's also used in Peter Pan, to describe the sword of Hook's first mate (the guy that's supposed to be lovable).
But he did invent a few words in that poem that have come to see common use, most notably chortal.
But he did invent a few words in that poem that have come to see common use, most notably chortal.