Achilles' Heel
idiom / noun /əˈkɪl.iːz hiːl/ — A fatal weakness in an otherwise strong person or system
Definition
A critical vulnerability in someone who is otherwise powerful or capable — the one point of weakness that, if exposed or attacked, can bring down the strongest system or person.
Beyond the definition
The Achilles' heel is the humbling detail of human greatness — every strength contains a weakness, every system a single point of failure. The word names the thing we protect most, because we know it could undo everything.
Origin & history
Greek mythology: Achilles was invulnerable except for his heel — the spot where his mother Thetis held him when she dipped him in the River Styx. He was killed when an arrow struck his heel.
Example sentences
Illustrative sentences for learning, not verified community posts or sourced quotations.
His perfectionism was his Achilles' heel — it paralysed him at the moments that mattered.
Every strategy has an Achilles' heel. The job is to find it before your enemy does.
She could negotiate anything — except when someone questioned her loyalty. That was her Achilles' heel.
How to use it
Follow this entry’s examples for grammatical form and sentence placement.
Choose “Achilles' Heel” when the meaning fits your context: A critical vulnerability in someone who is otherwise powerful or capable — the one point of weakness that, if exposed or attacked, can bring down the strongest system or person.
Synonyms
weakness, vulnerability, fatal flaw, soft spot
Antonyms
armour, strength, invulnerability
Related words
Achilles' Heel vs weakness
Weakness is a general lack of strength. An 'Achilles heel' is a singular, specific vulnerability that can lead to total failure, despite other strengths.
Word in the Wild
See how this word appears in life, language and stories.
Illustrative sentences and imagined stories for learning — not verified sightings, interviews, or sourced quotations.
Fictional scene
Small Crack Reveals Structural Vulnerability
A vibrant green shoot grows through a jagged crack in a marble floor beside a discarded brass compass.
The crack represents a single, critical point of weakness within a seemingly solid and powerful structure. Even a strong system can be undermined or brought down by one exposed vulnerability, just as the stone gives way here.
Image credit: Wordspun · AI-generated conceptual illustration
Questions about this word
What does "Achilles' Heel" mean?
Achilles' Heel is idiom / noun meaning: A fatal weakness in an otherwise strong person or system. A critical vulnerability in someone who is otherwise powerful or capable — the one point of weakness that, if exposed or attacked, can bring down the strongest system or person.
Where does the word "Achilles' Heel" come from?
Greek mythology: Achilles was invulnerable except for his heel — the spot where his mother Thetis held him when she dipped him in the River Styx. He was killed when an arrow struck his heel.