invulnerable
adjective
1. immune to attack; impregnable
- gunners raked the beach from invulnerable positions on the cliffs
Similar word(s): unconquerable, protected, safe, secure, airtight, bombproof, shellproof, defendable, defensible, entrenched, impregnable, inviolable, secure, strong, unassailable, unattackable, tight, sheltered, untouchable