shibboleth
noun [ C ] uk/ˈʃɪb.əl.eθ/ us/ˈʃɪb.əl.eθ/
formal过时的信仰;陈旧的习俗
a belief or custom that is not now considered as important and correct as it was in the past
They still cling to many of the old shibboleths of education. 他们仍然固守着许多过时的教育传统。
（特定人群的）特有用语（习俗等）
a word, phrase, custom, etc., only known to a particular group of people, that you can use to prove to them that you are a real member of that group