I Am Not Shazam: Sort of—the Spelljammer is a legendary Living Ship, spelljamming helms are the phlebotinum that powers space travel, and spelljammers can refer to ships (usually just "'jamming vessels") or sailors (as opposed to landlubbers, er, groundlings). Or only helmsmen.
Jeff Grubb: In the game we used it to describe the act of moving through space magically. And it was the class of ship that moved through space. And it was the proper name of the legendary Spelljammer, a supposed Flying Dutchman/White Whale. It was a noun, a proper noun, and a verb. If I could have made it an adverb I would have done that as well.