Adjectives

(a)inviolableincapable of being transgressed or dishonored“the person of the king is inviolable”, “an inviolable oath”
(s)impregnable, inviolable, secure, strong, unassailable, unattackableimmune to attack; incapable of being tampered with“an impregnable fortress”, “fortifications that made the frontier inviolable”, “a secure telephone connection”
(s)inviolable, inviolate, sacrosanctmust be kept sacred
(s)absolute, infrangible, inviolablenot capable of being violated or infringed“infrangible human rights”