or Achilles' heel
- a portion, spot, area, or the like, that is especially or solely vulnerable: His Achilles heel is his quick temper.
Origin of Achilles heel
- a small but fatal weakness
A point of vulnerability. (See Achilles.)
Idioms and Phrases with achilles' heel
A fatal weakness, a vulnerable area, as in This division, which is rarely profitable, is the company's Achilles' heel. The term alludes to the Greek legend about the heroic warrior Achilles whose mother tried to make him immortal by holding the infant by his heel and dipping him into the River Styx. Eventually he was killed by an arrow shot into his undipped heel. [c. 1800]