Both Oxford Online and Merriam-Webster dictionaries show grass roots with a space between the two words in the compound noun.

But this ngram shows substantially more hits for grassroots without a space separating the two nouns since the 1990s.

Which if either spelling is best to use today, and why?

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  • Actually no, because "grass roots" is still the nominal form, which an n-gram is unable to distinguish from an adjectival form "grassroots."
    – KarlG
    Dec 28, 2017 at 7:58
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    @KarlG Have you seen my ngram? It compares "grass roots are"/ "grassroots are"/ "grass roots have"/ "grassroots have".
    – JK2
    Dec 28, 2017 at 8:00
  • Ah, so it can distinguish. Sorry.
    – KarlG
    Dec 28, 2017 at 8:35
  • It would be reasonable to include further research in a question such as this. Other dictionaries (eg CED) give both spellings. 'Which is the correct noun spelling?' is not well phrased. You can choose which to use at the present time; however, it looks like the closed compound is becoming the favoured choice [Ngram results], so it is probably sensible to join the descriptivist camp now. Dec 28, 2017 at 8:53

1 Answer 1


Your question is certainly reasonable. I have noticed that dictionaries are somewhat slower than popular usage to pick up on spelling shifts that involve closing up hyphenated words or reducing two-word phrases to single words.

In the case of grassroots versus grass roots, Merriam-Webster's Eleventh Collegiate Dictionary (2003) lists grassroots as the preferred form for the adjective (with grassroot as an alternative) and grass roots as the preferred form for the noun. But as recently as the Ninth Collegiate (1983), MW offered no adjective form of the term, suggesting that it considered the normal form of the adjective to be either grass roots or grass-roots. That changed in the Tenth Collegiate (1993), when grassroots debuted as the preferred adjective form.

The Concise Oxford English Dictionary, tenth edition, revised (2002), meanwhile, echoes the Ninth Collegiate in offering only grass roots as the spelling for the noun form and no spelling for the adjective form.

For its part, The American Heritage Dictionary of the English Language, fifth edition (2010) lists grassroots as the only standard form for both the noun and the adjective. AHDEL came to this preference rather recently, however: in the fourth edition (2000), it listed grass roots as the noun form and grass-roots as the adjective form.

Clearly we are dealing with a term whose spelling is in flux—with Oxford holding to the traditional two-word or hyphenated spellings for the noun and adjective forms, Merriam-Webster opting for two words for the noun and one word (unhyphenated) for the adjective, and American Heritage endorsing the one-word form for both noun and adjective forms. My money, if I were a betting man, would be on the one-word form to triumph eventually, since the historical movement in spelling seems to favor it; but today we live in unsettled times, and the correct noun spelling of grass roots/grassroots depends on which authority you consult and how impressed you are by it.

Update (January 12, 2021)

To provide a bit of real-world context, I offer the following Ngram chart of word/phrase frequency for the terms "grass roots" (blue line) versus "grassroots" (red line) versus "grass root" (green line) versus "grass root" (yellow line) for the period 1900–2019:

This comparison is not subtle, in that it doesn't distinguish between "grass roots" as a noun, an adjective, or a subject and verb (for example). Nevertheless, it tracks a quite striking rise in frequency of "grassroots" from essentially zero prior to 1940 to a plurality of usage by 1980 to a dominant position over the past three decades.

On the strength of these results, it's easy to see why AHDEL, fifth edition (2010) has embraced grassroots as the standard spelling and why MW began treating grassroots as the preferred spelling of the adjective form of the term in 1993.

As Edwin Ashworth notes in a comment beneath this answer, it is a truism that—to the extent that it takes a descriptivist approach to orthography—a dictionary will necessarily be somewhat behind times on current real-world spelling preferences in instances where those preferences are changing rapidly. Still, it bears observing that many dictionaries seem to exhibit a degree of inertial resistance to change when it comes to presenting words that they have spelled a certain way in the past, even when the tide of popular usage has clearly changed; and this inertial force, at some point, becomes difficult to distinguish from evidence-denying prescriptivism. After 40 years of real-world dominance of the form grassroots over the form grass roots, I think, a dictionary's continued insistence that grass roots is the only (or even the primary) acceptable spelling of the term qualifies as almost purely prescriptive.

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    It may be splitting hairs of angels dancing on pinheads, but Oxford Dictionaries Online is calling this a plural (compound) noun, not an adjective like MW is. I'll need to wait till I get back from Christmas to check whether the real OED follows their custom of labelling such noun senses “attributive” in use. I honestly can’t quite convince myself one way or the other whether regular “is-it-an-adjective?” syntactic tests work here, like for instance deciding how acceptable in meaning and form something like “This movement is even more grassroots than that one is” strikes me.
    – tchrist
    Dec 29, 2017 at 10:18
  • @tchrist: Your cautionary note is well taken. I imagine that Merriam-Webster was thinking of a simple situation such as "grassroots [or grassroot] movement" when it made its move to one word for the adjective form. But the fact that adjectiveness and nounness tend to merge in settings such as the one you suggest is likely to add impetus to the movement toward rendering grassroots as a single word in all its parts-of-speech incarnations. The OED is unlikely to withstand that momentum much longer, I think.
    – Sven Yargs
    Dec 29, 2017 at 11:09
  • '[D]ictionaries are somewhat slower than popular usage to pick up on spelling shifts' is a truism. They can't pick up on them before they qualify according to their usage tests, which reflect popular usage. 'There's a considerable time lag ...'? (Had to look that up.) Jan 12, 2021 at 17:34

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