inviolable vs impregnable

inviolable and impregnable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
inviolable	No	Yes	No	No
impregnable	No	Yes	No	No

As adjectives, inviolable and impregnable are synonyms defined as:

inviolable and impregnable: immune to attack; incapable of being tampered with

Other synonyms of inviolable include secure, strong, unassailable, unattackable.

inviolable (adjective)	impregnable (adjective)
incapable of being transgressed or dishonored	capable of conceiving
not capable of being violated or infringed	immune to attack; incapable of being tampered with
immune to attack; incapable of being tampered with	incapable of being overcome, challenged or refuted
must be kept sacred