Impropriety is a synonym of inadvisability.
As nouns the difference between impropriety and inadvisability
is that impropriety
is (uncountable) the condition of being improper while inadvisability
is the quality or state of being inadvisable.
(uncountable) The condition of being improper.
(countable) An improper act.
The quality or state of being inadvisable.
:I had been warned of the inadvisability of disturbing sleeping dogs, so it did not surprise me when the wakened dog snarled at me.
*(quality or state of being inadvisable) foolhardiness, impropriety, imprudence, injudiciousness, rashness