'Shibboleth' definitions:

Definition of 'shibboleth'

noun

A favorite saying of a sect or political group [syn: motto, slogan, catchword, shibboleth]

noun

A manner of speaking that is distinctive of a particular group of people

From: GCIDE

Shibboleth \Shib"bo*leth\, n. [Heb. shibb[=o]leth an ear of corn, or a stream, a flood.]
1. A word which was made the criterion by which to distinguish the Ephraimites from the Gileadites. The Ephraimites, not being able to pronounce sh, called the word sibboleth. See --Judges xii. [1913 Webster]
Without reprieve, adjudged to death, For want of well pronouncing shibboleth. --Milton. [1913 Webster] Also used in an extended sense. [1913 Webster]
The th, with its twofold value, is . . . the shibboleth of foreigners. --Earle. [1913 Webster]
2. Hence, the criterion, test, or watchword of a party; a party cry or pet phrase. [1913 Webster]

Shibboleth river, or an ear of corn. The tribes living on the east of Jordan, separated from their brethren on the west by the deep ravines and the rapid river, gradually came to adopt peculiar customs, and from mixing largely with the Moabites, Ishmaelites, and Ammonites to pronounce certain letters in such a manner as to distinguish them from the other tribes. Thus when the Ephraimites from the west invaded Gilead, and were defeated by the Gileadites under the leadership of Jephthah, and tried to escape by the "passages of the Jordan," the Gileadites seized the fords and would allow none to pass who could not pronounce "shibboleth" with a strong aspirate. This the fugitives were unable to do. They said "sibboleth," as the word was pronounced by the tribes on the west, and thus they were detected (Judg. 12:1-6). Forty-two thousand were thus detected, and
"Without reprieve, adjudged to death,
For want of well-pronouncing shibboleth."