In classical mythology, the greatest warrior on the Greek side in the Trojan War. When he was an infant, his mother tried to make him immortal by bathing him in a magical river, but the heel by which she held him remained vulnerable. During the Trojan War, he quarreled with the commander, Agamemnon, and in anger sulked in his tent. Eventually Achilles emerged to fight and killed the Trojan hero Hector, but he was wounded in the heel by an arrow and died shortly thereafter.
Note: People speak of an “Achilles' heel” as the one weak or sore point in a person's character.
Note: The Achilles tendon runs from the heel to the calf.