The Bible’s Book of Judges recounts how, after the inhabitants of Gilead defeated the invading Ephraimite tribe, surviving Ephraimites attempted to cross the river Jordan back to their home territory. The Gileadites, having secured the river’s fords, identified fleeing Ephraimites by requiring them to say “Shibboleth”. As the Old Testament tells it, the Ephraimites “said Sibboleth: for he could not frame to pronounce it right. Then they took him and slew him”. The word shibboleth, from the Hebrew shibbólet שִׁבֹּלֶת, refers to the part of a plant containing the grain, such as the head of a stalk of wheat. Its significance lies not in agriculture, however, but in its pronunciation. In certain dialects, the initial consonant is pronounced “sh”, while in others, it is more of an “s”. Crucially, as in the biblical portrayal, such variation in pronunciation was used as an identifying feature of a group. The term shibboleth came to be used in English to refer more generally to a word or accent of a language variety (also to customs or beliefs) indicative of a speaker’s origin, and used to identify persons from another group or region by their differences. In other words, a shibboleth works as a password, serving to distinguish outsiders from insiders. Examples abound throughout history, with shibboleths often playing a dark role in war and genocide. The Sicilian word ciciri , meaning “chickpeas”, was used during the 1282 Sicilian Vespers rebellion to identify French occupiers of the island – French speakers use “sh” instead of “ch”, an “r” trilled at the back of the mouth rather than tapped using the tongue tip, and with stress on the final rather than initial syllable. The Spanish word perejil , for “parsley”, identified for execution Haitian immigrants at the Dominican Republic border in October 1937. During World War II in the Pacific, American soldiers used “lollapalooza” to identify Japanese infiltrators. And Sinhala words such as balthiya , “bucket”, were used in Sri Lanka’s anti-Tamil pogrom in Black July 1983. Where does the word ‘Omicron’, variant Covid-19 name, come from? A contemporary example has emerged in the ongoing Russian invasion of Ukraine: “Say ‘ palianytsia ’!”, demand Ukrainians of Russian soldiers and suspected saboteurs. Palianytsia , Ukrainian паляниця, is central in Ukrainian culture as a popular classic hearth-baked soft white wheat loaf, once reserved for festive occasions. With its Ukrainian pronunciation “pa-lya-NI-tsya” containing vowel and consonant sequences that are articulated differently by Russian speakers, the word palianytsia is even more significant now for its role as a shibboleth.