I recently wondered about the word "cantrip". It's used in the "Dungeons and Dragons" (D&D) role playing game, to mean "a small magic spell". I wondered if it has a meaning outside of D&D, and I don't think it does. If you google it, you mainly find D&D stuff, so in the present it is probably only used by people talking about role playing games (not exclusively D&D, as the concept is useful and has been adopted by other games as well).
From what I found online, the term existed before, originating from the Scottish language, describing a system of using meaningless syllables to encode a musical score for pipes. This system was later used by magicians and tricksters to add a little showmanship to their tricks, by mumbling these meaningless syllables as magic spells (think "abracadabra"). This led to the term meaning "magic spell", "witches spell" or simply "trick".
Apparently, some guy called "Gary Gygax", who wrote articles for the "Dragon Magazine", made a habit of using obscure words from the English dictionary and giving them specific meanings in D&D. In issue number 59 (March 1982), he wrote an article where he introduced cantrips to the game as very simple spells that would mainly have mundane uses for "would-be wizards". Since the word was already obscure at that time, it's safe to assume that it's even more obscure now, at least outside the world of role playing games.
That's at least the result of my research, which wasn't very thorough and I did not double check any sources, so believe it at your own risk (although the risk associated with false etymological facts is usually quite minor).
I like how this word was saved from being forgotten. It was one of these words that you'd come across in an old song or poem and have to look up in the dictionary to find out what it means. Now it is actually used again, if only by a small nerdy community. But it has the chance to catch on again and transcend this community. And I think it should. I think it's a really neat word.
