1. Immune to attack; impregnable
   "gunners raked the beach from invulnerable positions on the cliffs"

See also: airtight, air-tight, bombproof, defendable, defensible, entrenched, impregnable [rare], inviolable, protected, safe, secure, shellproof, sheltered, strong, tight, unassailable, unattackable, unconquerable, untouchable

Antonym: vulnerable

Encyclopedia: Invulnerable