from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A district associated with musicians, composers, and publishers of popular music.
- n. The publishers and composers of popular music considered as a group.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- proper n. The songwriting and publishing industry.
- proper n. District in New York City centered on 28th Street during the period roughly from 1885 to the 1920's where thousands of popular songs were commercially written.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a city district (originally in New York) where composers and publishers of popular music do business
Probably from tin pan, tinny piano + alley1 (from the cheap pianos associated with music publishers' offices).(American Heritage® Dictionary of the English Language, Fourth Edition)