The Hebrew word Shibboleth literally means "ear of wheat". In the Bible, the term was used to distinguish members of a group whose dialect lacked a "sh" sound, using an "s" in its place, from members of a group whose dialect included such a sound.
In modern parlance, the term is used for phrases that are used in a similar way—only members who belong to a certain group can use them "correctly." More loosely, "shibboleth" is also sometimes used for words or phrases that form part of the specialized jargon of a group, and reveal their users as members of a group.
- And the Gileadites seized the passages of the Jordan before the Ephraimites; and it was so, that when those Ephraimites who had escaped said, "Let me go over," that the men of Gilead said unto him, "Art thou an Ephraimite?" If he said, "Nay," then said they unto him, "Say now 'Shibboleth.'" And he said "Sibboleth," for he could not frame to pronounce it right. Then they took him and slew him at the passages of the Jordan; and there fell at that time of the Ephraimites forty and two thousand. (Judges 12:5-6, King James Version of the Bible)
- Scheveningen: Dutch people pronounce this word beginning with separate "s" [s] and "ch" [x]; a German would pronounce sch as [ʃ] = SAMPA [S]. The Dutch Resistance used this to ferret out Nazi spies during World War II.
- Ripley/ripply: If any distinction is made between the two words by a native speaker (rip-lee vs. rip-ul-ee), one will almost certainly not be made by a native speaker of Japanese. Either pronunciation would be very difficult to say properly as the English distinction between the R and L sounds is not present in Japanese.
- Leghorn: Allegedly, this word was used as a shibboleth during a war between the Chinese and Japanese, since the Japanese pronounced it as 'reghorn' (not being able to pronounce l), and the Chinese as 'legholn' (not being able to say English r). In fact, both Japanese and Chinese only have one phoneme /r/ (and no /l/ phoneme), with different allophones.
- Höyryjyrä: Finnish soldiers in World War II would use this as a password, as none but a true Finnish native speaker could properly say this word, which contains a difficult combination of Finnish ö, y, and ä vowels as well as the Finnish r. There's also a story about the Whites using "yksi" as a shibboleth in the Finnish Civil War. Communists were put to stand in line, and each one was asked to say "yksi". If the prisoner pronounced "juksi", he was a Russian foreign fighter and was shot.
- Rødgrød med fløde : This is the standard Danish shibboleth, which exposes the speaker's skill of pronouncing the Danish throat sounds.
- Fish and chips: Australians and New Zealanders sometimes tease each other on its pronunciation, usually as a joke. To Aussies, it sounds like Kiwis pronounce it "fush and chups", while Kiwis hear Aussies say "feesh and cheeps".
- The Spanish word perejil (parsley) was used as a shibboleth by Dominican Republic strongman Trujillo. See  .
- In his essay The Shibboleth of Fëanor, Tolkien describes how the Noldor elves change the sound th (SAMPA T) to s in the Quenya language. Strife occurs when the king's second wife adopts the name Indis (with an s) to emphasize her acceptance of Noldorin culture; however, king's son Fëanor considered this change to be an insult to his dead mother Therindë who had refused to be called Serindë.
- Unionized: Isaac Asimov introduced this shibboleth that distinguishes chemists from non-chemists. When reading this word aloud with no context, a chemist will pronounce it "un-ionized", whereas a non-chemist will pronounce it "union-ized".
- Coax: Information technology professionals often pronounce this as "co-ax", short for "coaxial cable", instead of as the English word "coax".