Shibboleth is a noun that refers to a use of language unique to a particular group.

Our word of the day comes from Hebrew. It means ‘ear of corn,’ but more importantly the word came to be used as a password to determine if someone was from the proper tribe. In more recent years, it simply refers to a word that is unique to a particular group of people.

For example: I used to think of the word ‘primo’ was a shibboleth among my group of friends in high school. But pretty soon I heard everyone saying. I guess the word wasn’t unique to us after all.