shib·bo·leth 
/ˈʃɪbələθ/ noun
plural shib·bo·leths /ˈʃɪbələθ/ noun [count] 1 : an old idea, opinion, or saying that is commonly believed and repeated but that may be seen as old-fashioned or untrue
▪ She repeated the old shibboleth that time heals all wounds. 2 : a word or way of speaking or behaving which shows that a person belongs to a particular group
▪ She repeated the old shibboleth that time heals all wounds.
