Ask our editors: Hyphenating comparative and superlative compound adjectives

A well-placed punctuation mark is the difference between ‘let’s eat grandma’ and ‘let’s eat, grandma’. But, nailing punctuation can be tricky, as the many questions we receive about it prove. Luckily, our team of editors are here to answer your questions.

Q: I read your ‘To hyphenate or not to hyphenate’ blog and noticed that the information relating to the hyphenation of compounds involving comparative and superlative adjectives does not appear to agree with other references, including the Chicago Manual of Style (CMOS).

I have always used a hyphen in phrases such as ‘fastest-growing business’, but you appear to disagree.

If you have any additional explanation, I would be interested in hearing it.

Thank you,


PS: I am an American, which, I am certain, explains everything.


A: Hi Patrick, thanks for getting in touch. Your mention of US English may be the best place to start answering your question.

Although Editor Group has offices and clients in Singapore and the US, our origins are in Australia. As such, this guidance is based on the Australian Government Style Manual – the Australian equivalent of the Chicago Manual of Style (CMOS) (or the AP Stylebook, if you prefer) – which has specific ‘no hyphen’ guidance for the ‘comparative/superlative adverb/adjective + participle’ construction.

Though CMOS doesn’t call out this particular construction, it does mention leaving some superlative compound modifiers ‘open’ (without a hyphen).

You might have seen, under 7.89 Hyphenation guide, 2. Compounds according to parts of speech, “adverb not ending in ly + participle or adjective”:

Certain compounds, including those with moremostless, least and very, can usually be left open unless ambiguity threatens.

The examples given include ‘most efficient method’ and ‘most skilled workers’ (most in number), with ‘most-skilled workers’ (most in skill) as an example where the hyphen may be necessary to avoid ambiguity.

As we mention in our blog post, we – like most style guides, including CMOS – recommend doing whatever produces the clearest, least ambiguous copy for your readers. So, regardless of the English variant, we would hyphenate something like ‘fastest-growing business’ if, in context, it could be misread as referring to a growing business that operates faster than other growing businesses, instead of a business that’s growing faster than other businesses.

All of that said, thank you for asking the question and bringing this potential for confusion to our attention. We’ve updated our final note on the blog post, so it reminds readers to also consider which English variant they’re working with, and the instructions of their local and/or in-house style guides.

I hope that helps, or at least offers food for thought. If you find this sort of thing interesting, you might enjoy Separated by a Common Language – no affiliation, just a great source of information and discussion on the differences between ‘Englishes’.

Kind regards,

Olivia McDowell

Senior Writer & Editor (New York)

Olivia McDowell is one of Editor Group’s writers and editors. You can read her excellent blog on hyphens – our most popular post ever – here. If you have a grammar or punctuation question, we’d love to hear from you.  

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To hyphenate or not to hyphenate

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