Shibboleth

iskulause

(a common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth)

uskomus

(a common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth)

šibbolet

(a word, pronunciation, or custom, distinguishing members of a group, especially as a test)