1. a word, phrase, or belief that distinguishes members of a particular group
2. an old idea, opinion, or saying that is commonly believed but may be wrong or meaningless

Examples

• Using certain technical terms became a shibboleth among the computer programmers.
• The ability to pronounce the local dialect correctly served as a shibboleth for identifying outsiders.
• He dismissed the old economic theory as just another shibboleth.
• The phrase became a political shibboleth used to test party loyalty.
• Many traditional sayings about success are merely shibboleths with little real meaning.
• The secret handshake was their shibboleth for club membership.