What's the "een" in Halloween?
1855, of uncertain origin. Earliest records of it are in San Francisco and Sacramento, California, U.S. Suggestions include Spanish chanada, a shortened form of charranada "trick, deceit;" or, less likely, German Schenigelei, peddler's argot for "work, craft," or the related German slang verb schinäglen. Another guess centers on Irish sionnach "fox."
A trick or bit of foolery; a mild cheat or deception
[1855+; origin unknown; perhaps fr Irish sionnachuighim, ''play tricks, be foxy'']