Synonyms for invulnerable

Adjective

1. invulnerable (vs. vulnerable), airtight, air-tight, bombproof, shellproof, defendable, defensible, entrenched, impregnable, inviolable, secure, strong, unassailable, unattackable, tight, untouchable, protected#1, secure, safe, secure, unconquerable

usage: immune to attack; impregnable; "gunners raked the beach from invulnerable positions on the cliffs"