Shibboleth
Part of speech: noun
Definition: A word, especially seen as a test, to distinguish someone as belonging to a particular nation, class, profession etc. A common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth.
Catchword
Part of speech: noun
Definition: A word under the right-hand side of the last line on a book page that repeats the first word on the following page.A word or expression repeated until it becomes representative of a party, school, business, or point of view.