Hyphens

When to use the hyphen

Hyphens are a matter of some contention! Even dictionaries and style guides don't always agree. For example, all three forms of this compound noun can be found:

river bed; river-bed; riverbed

This variation is due to the changing nature of language over time:

“The transition from space to hyphen to close juxtaposition reflects the progressive institutionalisation of the compound.”

(Huddleston, 1984)

The fact that English does not, unlike some other languages, have an academy to regulate it also impacts on this variation.

So we do not have clear rules on which words and phrases should have hyphens. However, there is some common usage which can guide you and help you to be consistent.

Hyphenate multi-word premodifiers

It is widely held that a hyphen should be used in a two-word or multi-word noun ‘premodifier’, that is to say, something which comes before the noun it modifies:

a research-heavy task

an up-to-date paper

However, these phrases are not usually hyphenated when they are ‘post-modifiers’, i.e. when they follow the noun:

the task was research heavy

the paper is up to date

Do not hyphenate adverb + adjective combinations

It is generally agreed that adverb + adjective combinations are not hyphenated:

internationally mobile groups

Distinguish between the hyphen and the dash

A hyphen (Sw. bindestreck) is used to connect two words or letters.

Note:

• There is no space between the hyphen and the word: over-compensate, signal-to-noise ratio, COVID-19, well-structured, eighteenth- and nineteenth-century scientists.

A dash (Sw. tankstreck) is used to show a range and could be read out as to: 2012–2017, 11 a.m.–4 p.m., Stockholm–Gothenburg.

Note:

• The dash is longer than the hyphen.
• There is no space to the left or right of the dash in these cases.

Avoid dashes in titles or for signalling a pause

In scientific writing, avoid using dashes to signal an interruption or pause in the text, as in They took their bags—and ran off. To introduce the second part of a title we recommend using a colon instead of a dash: Setting the seeds for green growth: A study of biofuel development in Indonesia's transport sector.

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References

Huddleston, R. (1984) Introduction to the Grammar of English. Cambridge University Press.