unattackable

Từ điển WordNet v3.1 - WordNet Dictionary

adjective

immune to attack;
incapable of being tampered with
- an impregnable fortress
- fortifications that made the frontier inviolable
- a secure telephone connection
• Syn:
impregnable, inviolable, secure, strong, unassailable
• Similar to:
invulnerable
• Derivationally related forms:
impregnability (for: impregnable), secureness (for: secure)

• Từ đồng nghĩa / Synonyms:
  impregnable, inviolable, secure, strong, unassailable