Suppose that you want to use a pair of bolt and nut to connect two things. However, the nut is like you can screw it forever and does not tighten!

What do you call this kind of nuts? Is there an adjective for them?

I would say the nut is broken, but I am not sure if that's the most common way of saying that.

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    FWIW, the nut could be fine and the bolt could be bad. – Tᴚoɯɐuo Dec 3 '18 at 20:06
  • The nut is not "broken" - it could simply be a mismatch with the bolt where the thread pitch is the same but the diameter is subtly different. – Criggie Dec 5 '18 at 23:35

I would say:

The thread has been stripped.

That is to say, the thread on either the nut or bolt has become damaged and can no longer support the load applied by the opposite thread:

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  • 3
    Right, screws of any kind are said to be stripped. Or alternatively, you can say threads are worn. – Lambie Dec 3 '18 at 19:17
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    @Lambie Though "worn" is much less specific. – David Richerby Dec 3 '18 at 21:30
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    Stripped is completely useless; worn is on the verge of being so. – Lambie Dec 3 '18 at 21:54
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    Worth adding that, in the same context and to the opposite, a nut and bolt that won't turn at all can be called 'seized'. – J... Dec 4 '18 at 13:26
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    @Ruadhan2300 that's the head being stripped, while Lee Mac says the thread is stripped (as I would). The equivalent to a stripped head on a nut on hex-head bolt would be something like rounded off, by the way – Chris H Dec 4 '18 at 16:37

In New Zealand and Australia we use the adjective munted to describe something (or someone) no longer capable of functioning, particularly screws, nuts and bolts that have been damaged by someone forcefully trying to turn them with the wrong tool. It is now more often used to describe people who are too intoxicated to function properly.

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    I am a 67yo Australian and I have never heard the word 'munted' in my life. – user207421 Dec 4 '18 at 5:38
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    Something about 'munted' makes me immediately understand what it means! – chasly - supports Monica Dec 4 '18 at 10:37
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    Whereas in England "munted" means "off your face" or "very drunk" / incapacitated, as used in Shaun Of The Dead. – John U Dec 4 '18 at 12:53
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    *not to be confused with a munter. – user68033 Dec 4 '18 at 13:59
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    @JohnU I can think of plenty of words meaning both "broken" and "incapacitated" a few of them may even be usable in poltie company. Slightly differently there's knackered (UK) =worn out/fatigued/(of a horse etc.) ready to be slaughtered – Chris H Dec 4 '18 at 16:40

In this case I would say

dodgy, broken, loose

I think outside of engineering most people would be grasping for some kind of synonym of broken

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    The problem with "broken" is that people are more likely to assume that it's cracked or broken into multiple pieces. – David Richerby Dec 3 '18 at 21:29
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    To me, saying it's "loose" implies that it can be tightened, which isn't the case here. – Kevin Dec 3 '18 at 21:52
  • Good points guys, cheers! – Jonathan Race Dec 5 '18 at 18:23

The nut is worn out. Or you can say This nut's threads are worn out.

Something that is worn out can no longer be used because it is so old or because it has been damaged by continued use:

Cambridge Dictionary

Damaged or shabby to the point of being no longer usable.

Oxford Dictionary


There is also crossthreaded. This probably isn't quite what you're going for, but it's related. In this case it feels tight and will not turn easily, but because the nut's threads and the bolt's threads are not properly aligned, it's not holding on with the desired strength.

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