Definition of Achilles heel in English:
A weakness or vulnerable point.
- This is my one weakness, my Achilles' heel, if you will.
- It seems to me that we have come to accept death on Earth as part of our human flaw, as our Achilles' heel.
- In the circumstances, worrying about being thought mad or humourless seems a peculiar Achilles' heel.
early 19th century: alluding to the vulnerability of Achilles.