The term originates from the Hebrew word "shibboleth" (שיבולת), 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 It derives from an account in the Hebrew Bible, in which pronunciation of this word was used to distinguish members of a group (the Ephraimites), whose dialect lacked a /ʃ/ sound (as in shoe), from members of a group (the Gileadites) whose dialect did include such a sound.
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 disguised refugees, the Gileadites put each refugee to a simple test:
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. Christians might have been familiar with the Biblical story and directly inspired by it, or might have independently invented the same method under similar circumstances. Modern researchers use the term "Shibboleth" for all such usages, whether or not the people involved were using it themselves.
The term "Shibboleth" is used in masonic initiation ceremonies.
Today, in the English language, a shibboleth has also a wider meaning, referring to any "in-crowd" 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 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. For example, people who regularly use words like "pr0n" and "filk" in conversation are likely members of computer culture or science fiction fandom, respectively. Shibboleths can also be customs or practices, such as male circumcision, or a signifier, such as a semiotic.
Cultural touchstones and shared experience can also be shibboleths of a sort. For example, people about the same age tend to have the same memories of popular songs, television shows, and events from their formative years. Much the same is true of alumni of a particular school, veterans of military service, and other groups. Discussing such memories is a common way of bonding. In-jokes can be a similar type of shared-experience shibboleth.
A notable if indirect reference to shibboleth in modern poetry is "the synagogue of the ear of corn" in Dylan Thomas poem, "A Refusal to Mourn the Death, by Fire, of a Child in London".
Shibboleths have been used by different subcultures throughout the world at different times. Regional differences, level of expertise and computer coding techniques are several forms that shibboleths have taken. For example, during the Battle of the Bulge, American soldiers used knowledge of baseball to determine if others were fellow Americans or if they were German infiltrators in American uniform. Some shibboleths are jokes.
During World War II, some United States soldiers in the Pacific theater used the word "lollapalooza" as a shibboleth to verbally test people who were hiding and unidentified, on the premise that Japanese people often pronounce the letter L as R, and that the word is an American colloquialism that even a foreign person fairly well-versed in American English would probably mispronounce and/or be unfamiliar with. In George Stimpson's A Book about a Thousand Things, the author notes that, in the war, Japanese spies would often approach checkpoints posing as American or Filipino military personnel. A shibboleth such as "lollapalooza" would be used by the sentry, who, if the first two syllables come back as rorra, would "open fire without waiting to hear the remainder.
In season 2 of The West Wing there is an episode called Shibboleth. The President tests the leader of a group of Chinese Christian refugees to establish whether they are just posing as Christians to gain asylum. The leader answers correctly before admonishing President Bartlet that "faith is the true Shibboleth".