What's the "een" in Halloween?
"informal session of folk musicians," 1940, American English, earlier "a gadget" (1927), of unknown origin, perhaps a nonsense word.
Another device used by the professional car thief, and one recently developed to perfection, according to a large Chicago lock-testing laboratory, is a "hootenanny," so-called by the criminals using it. ["Popular Mechanics," February 1931]
[one of many fanciful coinages for something unspecified; probably related to hooter, ''anything trifling,'' found fr the mid-1800s, and to hewgag, ''an indeterminate, unknown mythical creature,'' similarly found; the syllable hoo-, which is prominent in such coinages, probably represents the interrogative pronoun who; the folk-music sense is based on this, in spite of a fanciful explanation by the singer Woody Guthrie, involving a loud singer called Hootin' Annie]