A term you'll meet in Greek mythology and Homer's Iliad.
Achilles' heel means a single, often hidden point of vulnerability in something otherwise powerful or seemingly invincible. Most people assume the phrase comes straight out of Homer's Iliad. It doesn't — and that's the more interesting story.
Read the Iliad looking for the heel and you won't find it. Homer's Achilles is the greatest warrior at Troy, but he is mortal in the ordinary sense — not magically invulnerable except for one spot. The poem ends before his death, which is narrated only in later epic tradition that hasn't survived intact (a lost poem called the Aethiopis covered it), and nowhere in Homer is there any mention of Achilles being dipped in a river to make him invincible.
The familiar version — that Achilles' mother, the sea-nymph Thetis, dipped the infant Achilles in the River Styx to make him immortal, holding him by the heel, which the water never touched and which therefore remained his one mortal spot — first survives in writing in the Achilleid, an unfinished epic by the Roman poet Statius, written around a thousand years after Homer, in the 1st century CE. Statius is almost certainly drawing on older oral tradition, but the heel detail simply isn't in the Bronze Age or Archaic Greek sources closest to Homer. By the time later writers picked it up — Paris's arrow finding that one spot and killing Achilles outside Troy's walls — it had become the canonical version, and stayed that way.
The Iliad is where Achilles is most famous, so it's the natural place to assume the most famous fact about him lives. But the poem's actual interest in Achilles' vulnerability is different, and arguably more interesting, than a single weak spot: his fatal flaw is his rage and his pride — what the Greeks would later formalize as hamartia (see our entry on hamartia) — not a literal physical location. Homer's Achilles is undone by his own choices and temper long before any arrow finds his heel.
"Achilles' heel" now describes any single point of weakness in a person, plan, or system that is otherwise formidable — a company's Achilles' heel might be its supply chain; a chess grandmaster's might be time pressure. The idiom keeps the myth's shape — total strength undone by one exploitable gap — even though, ironically, that exact shape is something Homer's original epic never quite tells.
Lexio is a free Chrome extension and web app that reads a word's actual context and tells you what it means in this sentence, not from a generic dictionary.
Try Lexio — free →
Read deeper. Understand everything.
© 2026 Lexio · Privacy · Credits