The term originates from the Hebrew word shibbólet (שִׁבֹּלֶת), which literally means the part of a plant containing grains, such as an ear of corn or a stalk of grain or, in different contexts, “stream, torrent”. The modern usage derives from an account in the Hebrew Bible, in which pronunciation of this word was used to distinguish Ephraimites, whose dialect lacked a /ʃ/ phoneme (as in shoe), from Gileadites whose dialect did include such a phoneme.
Recorded in the Book of Judges, chapter 12, after the inhabitants of Gilead inflicted a military defeat upon the tribe of Ephraim (around 1370–1070 BC), the surviving Ephraimites tried to cross the Jordan River back into their home territory and the Gileadites secured the river’s fords to stop them. In order to identify and kill these refugees, the Gileadites put each refugee to a simple test:
Gilead then cut Ephraim off from the fords of the Jordan, and whenever Ephraimite fugitives said, ‘Let me cross,’ the men of Gilead would ask, ‘Are you an Ephraimite?’ If he said, ‘No,’ they then said, ‘Very well, say “Shibboleth” (שבלת).’ If anyone said, “Sibboleth” (סבלת), because he could not pronounce it, then they would seize him and kill him by the fords of the Jordan. Forty-two thousand Ephraimites fell on this occasion.
In numerous cases of conflict between groups speaking different languages or dialects, one side used shibboleths in a way similar to the above-mentioned Biblical use, i.e., to discover hiding members of the opposing group. Modern researchers use the term “shibboleth” for all such usages, whether or not the people involved were using it themselves.
Today, in American English, a shibboleth also has a wider meaning, referring to any “in-group” word or phrase that can be used to distinguish members of a group from outsiders – even when not used by a hostile other group. The word is less well recognized in British English and possibly some other English-speaking groups. It is also sometimes used in a broader sense to mean jargon, the proper use of which identifies speakers as members of a particular group or subculture.