1.Definition: immune to attack; incapable of being tampered with

"Fortifications that made the frontier inviolable"

Related Adjective(s):impregnable, secure, strong, unassailable, unattackable

2.Definition: incapable of being transgressed or dishonored

"The person of the king is inviolable", "An inviolable oath"

3.Definition: must be kept sacred

Related Adjective(s):inviolate, sacrosanct

4.Definition: not capable of being violated or infringed

Related Adjective(s):absolute, infrangible