uncensorable

As a noun censor

is (history) a roman magistrate, originally a census administrator, by classical times a high judge of public behavior and morality.

As a verb censor

is to review in order to remove objectionable content from correspondence or public media, either by legal criteria or with discretionary powers.

As an adjective uncensorable is

not censorable; that cannot be censored.

As adjectives the difference between censorable and uncensorable

is that censorable is capable of being censored while uncensorable is not censorable; that cannot be censored.