Is there a word or phrase to describe the worst flaw that someone has? The closest thing I have found to what I'm looking for is fatal flaw (technically called hamartia), but that's a bit too specific:

In tragedy, hamartia is the protagonist’s error or flaw that leads to a chain of plot actions culminating in a reversal from his/her good fortune to bad.


I'm not looking for a flaw that necessarily reverses someone's fortune, just a flaw that is worse than all of one's other flaws.

For example, John is disorganized, forgetful, and dishonest. If you think that dishonesty is John's worst flaw, you would say that dishonesty is John's __________.

  • 6
    I can't think of a single word, but I'd say it was his greatest shortcoming.
    – WS2
    Commented Mar 4, 2015 at 22:33
  • 3
    What is wrong with "worst flaw"?
    – GEdgar
    Commented Mar 4, 2015 at 22:48
  • 4
    How about vice?
    – ermanen
    Commented Mar 4, 2015 at 23:16
  • 2
    @GEdgar Talking about people's flaws seems awfully judgemental.
    – WS2
    Commented Mar 4, 2015 at 23:20
  • 1
    @WS2 "Biggest weakness" sounds rather less judgemental. But I like "greatest shortcoming".
    – Silverfish
    Commented Mar 5, 2015 at 1:01

10 Answers 10


Achilles' heel may fit your description:

  • a fault or weakness that causes or could cause someone or something to fail. (M-W)
  • Dishonesty is John's Achilles' heel!
  • 5
    A person's fatal flaw would be their Achilles heel. Also, I don't think it gets an apostrophe unless you're talking about his foot.
    – Mazura
    Commented Mar 5, 2015 at 3:58
  • 1
    @Mazura - It refers to his (Achilles') foot. en.wikipedia.org/wiki/Achilles%27_heel
    – user66974
    Commented Mar 5, 2015 at 7:59
  • 1
    So then, an Achilles heel doesn't get one and your Achilles' heel does?
    – Mazura
    Commented Mar 5, 2015 at 8:15
  • Not only mine. Main dictionaries use it referring to its methaphorical meaning. Though it is also used witout aphostrophe.
    – user66974
    Commented Mar 5, 2015 at 8:42
  • There's where I went first, but that's your greatest weakness, not flaw with ethical overtones.
    – ruffin
    Commented Mar 5, 2015 at 17:57

John is disorganized and forgetful, sure, but dishonesty may be his undoing.

  • 2
    I think "undoing" is more about something that will cause the person loss or hardship rather than being anything to do with being their "worst flaw". For example, "eating that sandwich was his undoing" has no implication of flaw.
    – Chris Down
    Commented Mar 5, 2015 at 15:03
  • @ChrisDown I see the distinction you're making. While undoing might refer to one's greatest flaw, it could also refer to an event that had dire consequences for the person.
    – Paul Rowe
    Commented Mar 5, 2015 at 17:20

For one word, how about downfall?

  • 1
    Downfall may well be due to an external event rather than an personal attribute.
    – brettdj
    Commented Mar 6, 2015 at 1:24

Demon could be a metaphorical expression for the extremely bad quality:


  1. a person, habit, obsession, etc, thought of as evil, cruel, or persistently tormenting

You're getting hung up on the finality of "fatal flaw", and many of these suggestions have a similar problem - the implication that this flaw will inevitably lead to a person's undoing. It's a difficult thing to untie from the concept of one's greatest flaw, since the strongest visual concept of a flaw that great is the fact that it can lead to a person's downfall.

I wouldn't worry about that implication, unless you very strongly want to untie it, because the use of such an idiom in english is usually figurative - a 'fatal flaw' doesn't necessarily mean the flaw will lead to a person's downfall, rather it only implies that the flaw is so great that it could lead to a person's downfall.

If you want to untie the concept of finality from this metaphor, you could try the expression "Key Flaw", which suggests a flaw that is more important and more disarming than any other flaw. And you could also simply use the adjective of 'greatest' to indicate that it is in fact their "greatest flaw". Both of these being a two-word phrase may not make it succinct, but the message of either phrase is quite clear.

As a final suggestion the weakest link refers to the most vulnerable part of a set, so if you're listing a person's characteristics or flaws, naming one as the 'weakest link' would indicate that it's the greatest flaw they have. But you wouldn't individually call it the 'weakest link' unless you have something it would be related to.

  • 1
    +1 An excellent point about how language really works in communication. In almost any context, when one hears or reads that something is someone's fatal flaw, it will translate as "greatest flaw", and unless the idea of the flaw leading to death or downfall is explicitly evoked, that notion will not be evoked! Commented Mar 5, 2015 at 16:40

You could use bane to express a person's worst flaw:

2 : a source of harm or ruin : curse


Dishonesty is John's bane.


Dishonesty is the bane of John's existence.

See What is the origin and meaning of the phrase “bane of my existence”?

  • 1
    Bane does not mean flaw. Commented Mar 5, 2015 at 16:40
  • Good answer; bane would be a good metonym for flaw to communicate the fact that it is the the one that ruins him. So far, two of the more popular answers use the same technique: undoing & downfall.
    – Good A.M.
    Commented Mar 5, 2015 at 23:29

"John is disorganized and forgetful but, of all his flaws, dishonesty would prove his greatest stumbling block."


In the Hebrew Bible, the term for "stumbling block" is mikshowl (מכשול), rendered in the Septuagint as skandalon (σκανδαλον). The English term "scandal" derives from this Septuagint Greek term skandalon, which in turn stands for the Hebrew mikshowl. The Greek term skandalon has little relation to the modern meaning of "scandal".

The Greek noun skandalon also has an associated verb, skandalizo (formed with the -iz suffix as English "scandalize"), meaning literally "to trip somebody up" or, idiomatically, " to cause someone to sin."

Apart from skandalon the idiom of "stumbling block" has a second synonym in the Greek term proskomma "stumbling." Both words are used together in 1 Peter 2:8; this is a "stone of stumbling" (lithos proskommatos λίθος προσκόμματος) and a "rock of offense" (petra skandalou πέτρα σκανδάλου). See, Wikipedia stumbling block"

"John is disorganized and forgetful, but of all his flaws, in the end it was his dishonesty that would snare (or, ensnare) him."

SNARE noun: a thing likely to lure or tempt someone into harm or error; “the wickedness and snares of the Devil” see, OED snare


You could always try saying that it is his weakness or failing.

Without any adjectives, these words give the impression that they are the defining unpleasant trait of the person's character.

If you say his biggest or worst failing/weakness, it puts the other flaws on an equal footing, and only defines this as the biggest of relatively equal flaws.

Whilst it was true that John was both disorganized and forgetful, his true weakness came from being dishonest.

John was regularly forgetful and disorganized, but his failing as a man came from his dishonesty.

Whilst they are not particularly strong words in and of themselves (we talk about 'weaknesses' all the time), used in this way it separates the one biggest flaw from the others, to iterate the point that the particular flaw you are describing is much worse than the rest.


While it is more often used to describe a process or series of events, you might consider nadir

The lowest point in the fortunes of a person or organization: they had reached the nadir of their sufferings

Oxford Dictionaries Online

You might say something like

While John is disorganized and forgetful, his dishonesty represents the nadir of [in?] his character.

  • This is kind of a stretch... but I almost like it better than any of the other suggestions here. This is the only suggestion that talks about character flaw rather than just weakness or vulnerability. Commented Mar 9, 2015 at 21:10

Hubris is extreme pride and arrogance shown by a character that ultimately brings about his downfall

In Greek tragedies, the “hubristic” actions of a hero, in a powerful position, causes his shame and humiliation.

(From literarydevices.net)

  • Hubris Might be an individuals worst flaw, but it certainly does not mean ' a person's worst flaw'. Commented Mar 9, 2015 at 21:09

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