Achilles' heel · 아킬레스건
fatal weak point; heel tendon
Today this word meansThe single weak spot of something that looks invincible. In anatomy, the tendon of the heel.
From the tale that when Thetis dipped her baby in the river, the heel she held him by never touched the water.
The anatomical term Achilles tendon was coined in the 1690s by the Dutch anatomist Verheyen, who took it from this story.
Worth noting
The heel story is not in Homer. It is a detail added in Roman times or later.