ACHILLES HEEL

a portion, spot, area or the like, that is especially or solely vulnerable. In Greek mythology, Achilles was an illustrious Greek warrior. He had been dipped in the river Styx (one of the mythological rivers of Hell) by his mother, which rendered him invulnerable except in the heel by which she held him. He was fatally wounded by an arrow in that heel. —DMSMH Glossary (app. 14.7.90)

a portion, spot, area or the like, that is especially or solely vulnerable. In Greek mythology, Achilles was an illustrious Greek warrior. He had been dipped in the river Styx (one of the mythological rivers of Hell) by his mother, which rendered him invulnerable except in the heel by which she held him. He was fatally wounded by an arrow in that heel.