shibboleth \SHIB-uh-luth\ noun
Meaning
1 : catchword, slogan
*2 : a widely held belief or truism
3 : a custom or usage regarded as distinctive of a particular group

I have long been of the opinion that women do not necessarily have less intelligence, just that they choose not to use it. I have known a number of very intelligent women, but when their husbands, who were much stupider than them, had an opinion, the women would stick to it, even if they knew it were wrong. Many consider this proof of their shibboleth, and fair cause for shutting up their women. But in all my time as pastor of the parish, I've never known anyone so clever as Mrs Wilson. So it was strange to me to find her standing over the body of her husband, a shotgun in her hands. She looked so calm, I could sense nothing but a great peace in her, a peace she had always been in conflict to reach.