Shibboleth

Shibboleth (Hebrew, meaning either an ear of corn or a flowing stream) became history's most famous linguistic test when the Gileadites used it to identify Ephraimite fugitives at the fords of the Jordan after defeating them in battle (Judges 12:1–6). The Ephraimites, whose dialect lacked the initial sh sound, pronounced the word as Sibboleth — and this phonological difference cost those who mispronounced it their lives. Forty-two thousand Ephraimites are said to have been killed in this manner.

The episode in Judges 12 arose from Ephraimite jealousy over being excluded from Jephthah's Ammonite campaign, paralleling an earlier complaint about Gideon (Judges 8:1). The word shibboleth has entered English and many other languages as a common noun denoting any password, test, or distinguishing practice that identifies membership in a group — a linguistic or cultural marker used to distinguish insiders from outsiders. Its entry into general usage reflects the enduring power of this biblical story as a parable of how dialect and custom reveal origins.