from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The way of proper conduct and moral integrity. Often used with the: kept strictly to the straight and narrow.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A path of honesty; procedure according to rules and plans.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the way of proper and honest behavior
Probably alteration of "Strait is the gate, and narrow is the way, which leadeth unto life” (Matthew 7:14).(American Heritage® Dictionary of the English Language, Fourth Edition)
Probably "strait and narrow," from Matthew 7:14 (Wiktionary)