unsayable

adjective

1. of the sort that can be said or spoken; utterable: He felt a great deal that was not sayable.
2. capable of being said or stated clearly, effectively, etc.: The speech is as sayable today as when Demosthenes first composed it.

adjective

1. too insulting, indecent, etc, to be said

noun

2. say the unsayable to express an opinion thought to be too controversial to mention