protection

arm, armament, munitions, weapon, weaponry

fastness, fort, fortress, palisade, stronghold

bodyguard, champion

lookout, sentinel, sentry, warden, warder, watch, watchdog, watchman

conserver, harborer, keeper, preserver, saver

aegis (also egis), cover, defense, guardianship, ward

guard, safeguard, screen, shield

asylum, harbor, haven, refuge, retreat, shelter

impregnability, impregnableness, invincibility, invincibleness, inviolability, inviolableness, invulnerability, invulnerableness