- a vulnerable spot or weakness
- a small fault in a person or system that can result in its failure
- a small problem or weak point in someone who is otherwise perfect
- a small but fatal weakness
- The corrupt minister is regarded as the government’s Achilles heel and is expected to resign.
- Though he was a good person, his short temper was his Achilles heel.
- The tennis player had a great serve, but his returns were not as good and that could prove to be his Achilles heel.
- The acquisition that the company made last year is turning out to be an Achilles heel, as it has not made any profits and is burning cash.
- Overall, they were a strong team, but there was a weak link in the defense, and that could prove to be the Achilles heel.
- He was a good student, but English literature had always been his Achilles heel.
- Fear of spiders was his Achilles heel.
The phrase has its origins in the legend of the Greek hero Achilles. According to the legend, Achilles was dipped into the river Styx by his mother Thetis to him invulnerable. The only portion of his body not immersed into the water was his heels, by which his mother held him. As a result, the heels were the only vulnerable part of his body. He was later killed by an arrow that struck his heel.
Though the legend is ancient, the phrase was not used in English until the 19th century. An early citation appears in an essay by Samuel Taylor Coleridge in “The Friend; a literary, moral and political weekly paper” in 1810.