Synonyms: inexpugnable, impregnable
Definition: incapable of being overcome, challenged or refuted
Usage: an impregnable argument; impregnable self-confidence
Similar words: unconquerable
Definition: not capable of being conquered or vanquished or overcome
Usage: a tribute to his courage...and his unconquerable will- R.E.Danielson; faced unconquerable difficulties
Synonyms: conceptive, impregnable
Definition: capable of conceiving
Similar words: fertile
Definition: capable of reproducing
Synonyms: inviolable, impregnable, unassailable, unattackable, strong, secure
Definition: immune to attack; incapable of being tampered with
Usage: an impregnable fortress; fortifications that made the frontier inviolable; a secure telephone connection
Similar words: invulnerable
Definition: immune to attack; impregnable
Usage: gunners raked the beach from invulnerable positions on the cliffs