A ground zero is the location under an explosion in the air.
Like the places in Hiroshima and in Nagasaki.
The term is often used to refer to the New York City site of the September 11 attacks in 2001. Both 1 World Trade Center and 2 World Trade Center were attacked separately, but ended up as one joint pile of debris. So there is only one ground zero in Manhattan. The nuclear explosions in Hiroshima and Nagasaki resulted in two of these locations. But what is the term for multiple air burst sites?

I think it is one of the following four:

  • ground zeros

    • This could represent both (ground zero)s or ground (zeros). I can describe the two distinct identity elements of two mathematical groups as two zeros, and a ground related to the zeros would be called ground zeros.
  • ground zeroes

    • This describes a single ground which is zeroing.
  • grounds zero

    • This describes the zero location of multiple grounds, which share the same zero, so that would fit the case of multiple airburst sites, but it depends on that both places are are compared in one coordinate space and therefore share the same zero.
  • grounds zeros

    • This would be strange as it involves the plural twice, so it should describe at least four elements, at least two grounds multiplied by at least two zeros, and we have two places, not four.

Of course it could be none of them.

So what is it, and why?

  • Even if one of the options above is correct, there's probably a better way to articulate the message you want to convey, as none of those terms sound good or are in common use. Sep 4 '19 at 16:33
  • I'm not sure I've ever seen a context where I'd want to use a term that pluralizes "ground zero", but my inclination would be to use "grounds zero", analogous to "attorneys general" being the plural of "attorney general", or "courts martial" being the plural of "court martial". Sep 4 '19 at 16:36
  • @Michael_B Actually, I came across a use of "ground zeroes", an assumed it refers to multiple places - the context did not provide a clue. Turned out if does not refer to any place at all. Sep 4 '19 at 16:44
  • @JeffZeitlin Good point, "attorneys general" is pretty confusing to me, but I thought that's because I expect "general attorneys" just as I expect "general attorney" Sep 4 '19 at 16:49
  • @JeffZeitlin I do not want to use it either, but I thought I had seen it being used as "ground zeroes". Turned out I had actually seen a use of the verb to zero. Sep 4 '19 at 16:55

Grounds zero is unheard of in Google Books, in contrast to ground zeros and zeroes (both zeros and zeroes being acceptable pluralizations of zero).

Google NGram showing no results for 'grounds zero'

(While the above includes many coincidental colocations, as at sentence breaks, almost all results after World War II relate to ground zero in miltiary or civil defense contexts, referring to the point on the ground below the detonation of a nuclear device.

A search on it in other corpora turns up, almost exclusively, titles from some of the laziest editors anywhere for articles or screenplays related in some way to coffee and used coffee grounds.

Ground zero, as with point zero, is a set phrase referring to a specific location. Zero is not a measure or count, nor a postnominal adjective; ground zero is not analogous to saying phases three and four of the project, or the succeeding poets laureate.

Consider, for example, from the August 1, 1946 issue of the Bulletin of the Atomic Scientists:

At Hiroshima, for example, persons in a concrete building 3,600 feet from ground zero…

They were 3600 feet from ground zero, not at ground 3600, or ground 0.68 miles, or ground 1097.3 meters for what it's worth.

  • @EdwinAshworth Better?
    – choster
    Sep 4 '19 at 18:35
  • Oh, Grice would be chuffed to bits. Sep 5 '19 at 10:34

ground zeros or ground zeroes

While "ground" and "zero" are both both adjectives and nouns on their own, "ground zero" is a compound noun in which neither "ground" nor "zero" serves as noun or adjective of the other but in their entirety as a phrase are a noun. As such, "ground zero" gets pluralized in its entirety as a phrase, meaning the pluralizer comes after the entire thing rather than parsing out a particular noun within it. This is borne out by usage as Google Ngram shows myriad examples of it being pluralized in published works as "ground zeros" or "ground zeroes" but no examples of it being pluralized as "grounds zero," grounds zeros," or "grounds zeroes."

As for whether to use "es" or just "s" to pluralize it, it would follow how "zero" is normally pluralized when it is by itself. There have been several questions on Stack Exchange sites that give excellent answers regarding "zeros" versus "zeroes" as regards pluralization of "zero" and as regards pluralization of "zero" when found in a compound noun (e.g., double zero), including:

Upon reviewing those answers, we may surmise that what it boils down to is personal preference. That is unless you are beholden to a particular style guide that requires either "es" or "s" for pluralization after instances of "zero."

Dissenting Opinion:

simply ground zero (not ground zeros or ground zeroes)

I did find one source that disagreed with this: Collins Dictionary defines "ground zero" as a noncount noun.

If a nouncount noun or if being used as such, it would not take any pluralization. Pluralizing it would indicate types of ground zero and not plural locales. It being a nouncount noun, or striclty a nouncount noun, is not borne out by usage, though, as evidenced by Google Ngram.

English being a descriptive rather than prescriptive language, the multitudinous use of "ground zero" as a count noun descriptively indicates that it is at the very least also a count noun.

Nevertheless, I would be remiss not to mention this, for what this means is that an alternative to "ground zeros" or "ground zeroes" is simply "ground zero," for example, "ground zero of Hiroshima and Nagasaki," which, of course, could be misconstrued as each sharing the same ground zero, but that is the nature of nouncount nouns, no different than saying "information of Hiroshima and Nagasaki" possibly being misconstrued as shared information when each has different information.

Incidentally, not pluralizing and simply saying "ground zero" is further underpinned by the presence of "ground" in the noun "ground zero." Just like the rules for the pluralization of "zero" have bearing on how we treat "ground zero," we could surmise grammatical rules for its individual elements might also extend to the treatment of the whole, and since "ground" is generally treated as a nouncount noun (e.g., "The ground of Hiroshima and Nagasaki was irradiated by..."), the validity of using "ground zero" as a nouncount noun is further underpinned, which, by the way, doesn't disprove using it as a count noun.


Where a noun is modified by a post-positive adjective (or attributive noun, like zero), it is still the noun which is pluralised. Adjectives are not inflected for number.

Thus: Postmasters General, heirs apparent, monsters unseen¹, etc. So, strictly, grounds zero.

There are a couple of issues with grounds zero:

  • It's actually difficult to say;
  • It's accepted as a single compound noun rather than a post-positive adjective. OED lists it as "ground zero n." under ground.

So ground zeros would not be entirely out of the question². The plural of zero can be spelled zeros or zeroes — OED has both in its citations.

¹ "They felt surrounded by monsters unseen"; poetic, but not unusual.
² So this answer can't be definitive: either is possible.

  • Arguably, fixed phrases consisting of noun + numeral follow a different pattern. 'Lest We Forget the Other September Elevens'. But they're rare, and arguably compounds, as you suggest. Sep 4 '19 at 18:17
  • "September Eleven" is English?
    – Andrew Leach
    Sep 4 '19 at 18:19
  • Too soon after tea for a better example. 'Announced at SolidWorks World 2016 in the beginning of February, the first Mark Twos started shipping to customers before the end of ... ' [TheManufacturer.com]. Plus many other examples. Sep 4 '19 at 18:24
  • 1
    Ground zero is the point on the surface closest to the event. So, arguably, the word "ground" is the modifier. It's the ground location of the zero, the zero being the vertical line through the event. It can also be called the surface zero. Though, as near as I have been able to tell, there is no specific word for the zero right at the event when it's above ground. Below ground it's the epicenter. For earthquakes ground zero is also the hypo-center.
    – puppetsock
    Sep 4 '19 at 21:26
  • It's not long after a meal again, but that may not be the reason no postnominal attributive noun examples are springing to mind. Sep 5 '19 at 10:37

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