impregnable 11 Associations

inexpugnable unconquerable (similar term)

inexpugnable 12 Associations

impregnable unconquerable (similar term)

unconquerable 13 Associations

impregnable (similar term) inexpugnable (similar term) indomitable (similar term) never-say-die (similar term) unsubduable (similar term) insuperable (similar term) insurmountable (similar term)