Words–Shibboleth

From m-w.com:

1. a : a word or saying used by adherents of a party, sect, or belief and usually regarded by others as empty of real meaning <the old shibboleths come rolling off their lips — Joseph Epstein>

1. b : a widely held belief <today this book publishing shibboleth is a myth — L. A. Wood>

1. c : truism, platitude <some truth in the shibboleth that crime does not pay — Lee Rogow>

2. a : a use of language regarded as distinctive of a particular group <accent was…a shibboleth of social class — Vivian Ducat>

2. b : a custom or usage regarded as distinguishing one group from others <for most of the well-to-do in the town, dinner was a shibboleth, its hour dividing mankind — Osbert Sitwell>

More info:

http://en.wikipedia.org/wiki/Shibboleth