In Harry Potter and the prisoner of Azkaban I came across a sentence:

  • Bad blood will out.

The context is this: Aunt Marge while sitting at the table is talking about Harry's parents who she thinks have bad blood. She is saying that eventually a sibling of such parents won't be any better and bad blood runs in Harry's veins either.

I understand that "out" here is a verb and I understand by the context what it can mean. I would like to know - if we were to use a different verb or phrase then what would it be?

I'm thinking of "reveal itself" or "stand out". What other options are there?

P.s. is this verb "to out" common?

  • You really need to give a sentence in which you provide the subject of this verb you're seeking. Or is "bad blood" the subject?
    – TimR
    Dec 25, 2017 at 18:26
  • @Tᴚoɯɐuo The sentence is as is and I quoted it straightforward. Dec 25, 2017 at 19:10
  • I mean, do you want to say "Bad blood _______?" or are you looking for a general-purpose synonym for the intransitive verb out, which can be used with things other than bad blood?
    – TimR
    Dec 25, 2017 at 20:33

2 Answers 2


"X will out" is an idiomatic expression, that means (as you guessed) that some distinctive negative quality in a family will reveal itself (in the children) in time.

As far as I know it's only used for negative (presumably hereditary) qualities, and not positive qualities. For those there are different expressions:

She has a noble lineage.

Hard work and tenacity are in her blood.

Creativity runs in her family.

and others. Although the last two can also be negative.

Her parents were criminals, and, mark my words, she'll be one too. Larceny runs in her family.

  • 4
    I don't know that it's negative, so much as it is referring to something someone is hiding, which tends to be negative. The phrase I think it comes from is "the truth will out".
    – ColleenV
    Dec 25, 2017 at 17:52
  • @ColleenV good point, I knew there was another variation that I couldn't recall. Although even "the truth will out" has a negative context, that someone has deliberately hidden the truth. I can't think of a case where "X will out" suggests an as-of-yet unseen positive quality that will reveal itself in time, can you?
    – Andrew
    Dec 25, 2017 at 17:58
  • The truth isn’t a positive or negative thing in and of itself unless you’re the one lying ;) You’re correct though that the truth that will out is generally unpleasant.
    – ColleenV
    Dec 26, 2017 at 11:47
  • 3
    @ColleenV Don't forget "Murder will out" a very common if now old-fashioned phrase. That is not at all a hereditary quality, although it is one both hidden and negative. Jun 3, 2019 at 23:15

out (v.)

Old English: utian "expel, put out"; used in many senses over the years.

[... (modern meanings of the verb, "out")]

sense of "disclose to public view, reveal, make known" has been present since mid-14c.

Example: "Eufrosyne preyde Þat god schulde not outen hire to nowiht." [Legendary of St. Euphrosyne, c. 1350]

Related: Outed; outing.



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