Meaning : Immune to attack. Incapable of being tampered with.
Example :
An impregnable fortress.
Fortifications that made the frontier inviolable.
A secure telephone connection.
Synonyms : inviolable, secure, strong, unassailable, unattackable
Meaning : Capable of conceiving.
Synonyms : conceptive
Meaning : Incapable of being overcome, challenged or refuted.
Example :
An impregnable argument.
Impregnable self-confidence.
Synonyms : inexpugnable