<p>A second is sometimes added to compensate for the slowing down of the Earth's rotation, these are called &quot;leap seconds&quot; by analogy with &quot;leap years&quot;. There has been a decision to abandon leap seconds sometime before 2035, and moreover the Earth is now spinning faster, meaning that there may be a need to do the opposite of adding a second, that is skipping a second.</p>
<p>What do you call the opposite of a leap second?</p>
<p>Would the same term be used for the opposite of leap years (I'm talking about a planet that takes, for example 364.75 days where we make a correction by subtracting a day every four years?</p>

CC BY-SA 4.0
2023-03-03T23:21:47.720Z
https://en.wikipedia.org/wiki/Common_year I doubt there's a standard term for negative leap years, but I guess some scifi authors may have coined names for them.
PM 2Ring
CC BY-SA 4.0
2023-03-03T23:50:50.210Z
There is no word. Why would you suppose there is one.  A sci fi writer might have invented a word, but that is then a matter of opinion.
James K
CC BY-SA 4.0
2023-03-04T13:16:38.850Z
You may as well ask why we use "leap" for the real case.  If the year were shorter, our antecedents would have coined a word for it and not for the real case.
Chenmunka
CC BY-SA 4.0
2023-03-04T19:24:32.987Z
This might be solved, sort-of. The Earth's rate of speed-up of rotation is slowing down; there's a chance that some time in the next century the same criteria that are used to add one second in some years will require removing a second: (56, 57, 58, 0, 1, 2...) so it's possible that some term has been circulated and accepted, at least among leap-second scientist circles :-)
uhoh
CC BY-SA 4.0
2023-03-05T06:47:27.470Z
@uhoh They're just called negative leapseconds. See https://raw.githubusercontent.com/eggert/tz/main/leap-seconds.list
PM 2Ring
CC BY-SA 4.0
2023-03-05T06:52:59.570Z
@uhoh Over the long term, the Earth's rotation is slowing down, transferring angular momentum to the Moon. However, there are short-term irregularities that affect the need for leapseconds. We've never needed negative leapseconds (so far) because the SI second corresponds to the mean solar second of ~1820, so it's a bit shorter than the current mean solar second.  I have details & some links at the end of this: https://physics.stackexchange.com/a/677946/123208
PM 2Ring
CC BY-SA 4.0
2023-03-05T10:01:19.617Z
I've taken the liberty of following up on your comment about "it should have been about leap seconds" to make it about leap seconds.  That is (it think) an answerable question. You can rollback my edit if you disagree.
James K
CC BY-SA 4.0
2023-03-05T23:59:00.387Z
An article on negative leapseconds by Demetrios Matsakis, former head of USNO’s Time Service Department. https://www.masterclock.com/will-we-have-a-negative-leap-second.html
PM 2Ring
CC BY-SA 4.0
2023-03-29T20:57:41.570Z
There is a word @JamesK
Starship
<nomenclature>
What do you call the opposite of a leap second?
Scott Bordelon
# What do you call the opposite of a leap second?

(Asked by: username_0 on 2023-03-03)

A second is sometimes added to compensate for the slowing down of the Earth's rotation, these are called "leap seconds" by analogy with "leap years". There has been a decision to abandon leap seconds sometime before 2035, and moreover the Earth is now spinning faster, meaning that there may be a need to do the opposite of adding a second, that is skipping a second.

What do you call the opposite of a leap second?

Would the same term be used for the opposite of leap years (I'm talking about a planet that takes, for example 364.75 days where we make a correction by subtracting a day every four years?

**Tags:** nomenclature

> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Common_year I doubt there's a standard term for negative leap years, but I guess some scifi authors may have coined names for them.  
> **username_2**: There is no word. Why would you suppose there is one.  A sci fi writer might have invented a word, but that is then a matter of opinion.  
> **username_3**: You may as well ask why we use "leap" for the real case.  If the year were shorter, our antecedents would have coined a word for it and not for the real case.  
> **username_4**: This might be solved, sort-of. The Earth's rate of speed-up of rotation is slowing down; there's a chance that some time in the next century the same criteria that are used to add one second in some years will require removing a second: (56, 57, 58, 0, 1, 2...) so it's possible that some term has been circulated and accepted, at least among leap-second scientist circles :-)  
> **username_1**: @username_4 They're just called negative leapseconds. See https://raw.githubusercontent.com/eggert/tz/main/leap-seconds.list  
> **username_1**: @username_4 Over the long term, the Earth's rotation is slowing down, transferring angular momentum to the Moon. However, there are short-term irregularities that affect the need for leapseconds. We've never needed negative leapseconds (so far) because the SI second corresponds to the mean solar second of ~1820, so it's a bit shorter than the current mean solar second.  I have details & some links at the end of this: https://physics.stackexchange.com/a/677946/123208  
> **username_2**: I've taken the liberty of following up on your comment about "it should have been about leap seconds" to make it about leap seconds.  That is (it think) an answerable question. You can rollback my edit if you disagree.  
> **username_1**: An article on negative leapseconds by Demetrios Matsakis, former head of USNO’s Time Service Department. https://www.masterclock.com/will-we-have-a-negative-leap-second.html  
> **username_5**: There is a word @username_2  

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## 0 answers

