A hyphen is this short punctuation mark: – . Not to be confused with longer dashes, which have different uses. Hyphens are used in English for two specific purposes – hard hyphens join words together, while soft hyphens divide words. The uses of hyphens can depend on certain styles, but generally they are used in the patterns laid out below.

Compound Words

Compound words, when we combine different words for a particular purpose, can come in three main forms: separated by a space, joined by a hyphen or joined as one word.

coffee cup
anti-inflammatory
newspaper

The conventions used can change over time – new compound words may be separated by a space, and get hyphenated as they become more popular, and finally get combined into one. This often happens when we start combining two nouns for a new idea, or when we frequently add a prefix or suffix to a word. Hyphens are also used in compounds where they help with pronunciation or to separate awkward letter combinations.

Compound modifiers are often hyphenated before a noun when they form a combined modification, for example German-speaking people or stainless-steel knife. These compounds aren’t usually hyphenated after the noun, however (e.g. a knife of stainless steel).

Be careful to note whether your modifiers form one unit or not – a hyphen can change whether the first modifier affects the whole noun phrase or is combined with another modifier. A long tailed lizard, for example, could be a lizard that is long and has a tail, while a long-tailed lizard is a lizard with a long tail.

Compound descriptors beginning with adverbs ending –ly are not usually hyphenated, such as newly discovered or frequently seen.

Hyphens are also not used for compounds of proper nouns, with capitalised words, such as New York subway or Russian Orthodox churches. Likewise, scientific terms and foreign phrases aren’t typically hyphenated, though in some cases they are when it helps demonstrate a specific meaning.

Prefixes

Though we usually combine words when using prefixes, hyphens may be used to separate a prefix when it may avoid mispronunciation or confusion. This is most frequently seen when a word combines the same vowels or consonants, or if the combined word could otherwise be confusing.

re-enter
pre-eminence
de-ice
pro-life

This is less common in US English, and with common words such as cooperate.

Hyphens may also be used to avoid confusion with repeating a prefix, or when the combined word already exists with a different meaning.

re-release (repeated prefix)
re-sign (repeat a signature, as opposed to quit)

Prefixes before a capitalised name, number or date are usually hyphenated.

pro-Obama
pre-1800s
mid-December

Suffixes

Suffixes are never spaced, so they either use a hyphen or are combined with the root word. Hyphens are usually used to avoid combining similar letters, for example if you already have two of a consonant before a suffix starting with the same consonant (shell – shell-less).

Hyphens are also used for new suffix combinations, particularly with –like, though commonly used terms can become combined.

a cheese-like substance (less common)
catlike reflexes (common and accepted)

In general, then, the more common and widely used the suffix, the less likely it needs a hyphen.

Names

Hyphens are often used in compound and double-barrelled personal names, and for some companies and places where two entities have been combined. Hyphens are also used for joint enterprises, such as when two creators are joined to form something together.

Mary-Anne
Coca-Cola
Sino-Soviet Pact

Numbers

Hyphens are used in written numbers under one hundred (e.g. twenty-two, ninety-eight). We don’t use hyphens for hundreds, thousands and above. So, 13,453 would be written thirteen thousand, four hundred and fifty-three. Hyphens are also used in fractions, such as one-half and three-quarters.

Hyphens may also separate numerical figures, such as phone numbers: 123-777-000.

Compass directions

Hyphens are usually used to separate compass points for directions, though sometimes these are combined as compound words (more common in the US).

north-east
south-west

Common modifiers

Hyphens are used in a series when multiple modifiers refer to one thing.

two- and three-litre jugs
postmen and –women

Interrupted words

Hyphens can indicate breaks in words, for example when a word is stammered, drawn out or has another word interjected in the middle. This is mostly used for dialogue or in creatively recreating sounds.

“P-p-please,” he said. “Let me in from the cold!”
“Abso-blooming-lutely!”
The door made a ch-ch-chick sound as she unlocked it.

Divided words

Hyphens can also split words for the sake of typography, without necessarily interrupting or changing the word. This is particularly used when a long word comes at the end of a line in printed text. Such divisions are usually done between syllables – and there are varying rules for when a break is acceptable or not. In general, single-syllable words (including longer words pronounced with a single syllable) should not be divided and breaks should not divide letter groups that are pronounced together.

Words with certain endings such as –ed, -ted and –er aren’t usually divided, and you should avoid dividing words when it leaves less than three letters in one line.

For words that are already hyphenated, we usually divide them at the hyphen rather than introducing a second division. Similarly, with combined compound words it makes most sense to divide them along the original compound (e.g. tele-vision), as long as it doesn’t change the combined pronunciation (e.g. chil-dren not child-ren).

Most gerunds can divided at the –ing, or between the double-consonant of the -ing (e.g. cook-ing, drop-ping).

Generally it’s best to avoid dividing names.

This is a brief look at hyphen conventions in English – there are additional minor rules to consider, and regional variations, and hyphenation can be very specific for different words, so if in doubt do check. It’s worth noting, too, that these are the major rules for hyphens – and for purposes that fall outside these categories (such as parenthetical information and separating clauses) the hyphen is not used; that is the domain of dashes.