Wear off 徐々に薄らぐ

The lesson wore off in less than a month. 

futile = fruitless /ˈfjuːtʌɪl/

Another museum visit would probably be futile. 

contrite

Now she was contrite.

shibboleth 無意味な考え

For Greene and others in the Trumpist wing of the Republican Party, anti-history has become a shibboleth. 

https://www.theatlantic.com/ideas/archive/2021/07/republicans-anti-history-marjorie-taylor-greene/619403/