Textual thesaurus for "impregnable"

(adj) inexpugnable

incapable of being overcome, challenged or refuted

an impregnable argument; impregnable self-confidence

(adj) conceptive

capable of conceiving

(adj) inviolable, unassailable, unattackable, strong, secure

immune to attack; incapable of being tampered with

an impregnable fortress; fortifications that made the frontier inviolable; a secure telephone connection