incapable of being wounded, hurt, or damaged; safe from attack.
From Greek Mythology:
Achilles was invulnerable except for his heel.
Homer's Iliad was the Story of Achilles that Alexander the Great took with him as a bedside book on his adventurous campaigns.
Achilles was son of Peleus and Thetis, and the greatest of all Greek warriors. When Achilles was an infant his sea-goddess mother, wishing him to share her immortality, dipped him into the river Styx. However, in doing so, she held him by the heel, and the part of his heel covered by her thumb became his one vulnerable spot. Otherwise, his hide was stronger than armour. He could not be wounded by any weapon wielded by man. |