impropriety means "improper action or behavior" examples:
Margo's impropriety was that she never wrote "thank you notes".
View page
My actions have created an air of impropriety for you, your
family and mine.
View page
The woman's impropriety made her the talk of the town.
View page
In some homes it is considered an impropriety if you don't
remove your shoes before entering, in others it is considered an
impropriety to remove your shoes unless invited to do so.