Hyphens -

A hyphen links words together as well as their meanings.

We have two kinds of words relating to compositions:
Root words and compound words.
Examples:
Fore is a prefix.
Seen is a root.
Foreseen is a compound word.


1. Solid word
A solid word does not contain a hyphen.
Examples:
Butterfly, powerhouse, grandstand, headline, spendthrift, 
spellbound, colorblind, whiplash, payroll, blowtorch, 
panhandle, playpen, railroad, …

Note: Some verb forms are built as separate words and 
as one word when used as nouns.
Examples:
Shut down, break down. (Verbs)
Shutdown, breakdown. (Nouns)

2. Compound words
Words connected together as a compound may be
written separately, written as one word, or connected by 
hyphens.

Compound words uses hyphens to connect two or more words .




Hyphen:
A hyphen is represented by “-” (not -- which means a dash).
It connects:

Prefixes and suffixes to words,
Words, parts of words, or compound words, and
Syllables of words broken at the ends of lines.


General cases:
Use a hyphen:

In writing fractions and all numbers from 21 to 99 
(compound numbers)
Examples:
 
Three-fifth, 
Seventy- six
 figures or letters.
Examples:
T-shirt
Mid-1980s
5-speed
H-Bomb
Between the words of a group of words taking the place 
of a single adjective (act as a single idea) before a noun. 
Examples:
Well-known 
Fifteen-years old boy.

However, when compound modifiers come after a noun, they 
are not hyphenated:
Example:
He is fifteen years old.

Smart old man. No hyphen is used because smart and old are 
two separate ideas.
To make the sentence clear, use a hyphen when its 
lack creates confusion.
Example:
Before reduction-on-prices.
Before-reduction on prices.


Using prefixes:
Hyphenate:

To separate the parts of a compound word using the prefixes.
Hyphenate onto root words the following prefixes:
Re-, all-, quasi-, ex-, self-, quarter-, quasi-, half-.

Hyphenate with "re" only when it means again, and if it’s omitted, the 
hyphen will cause confusion with another word.
Examples:
 
Recover, remove: Re does not mean again: Don’t use a hyphen.
Re-covered: Re means again and the omission of the hyphen may cause 
a confusion 

with another word:  Use a hyphen 
            Reissued:  Re means again but the omission of the 
			hyphen doesn’t cause a confusion 

with another word:  Do not use a hyphen.
 all words with the suffix self. Except: selfish and selfless.
Examples:
  
Self-consistence
Self-respect
 prefixes when they come before proper nouns or adjectives.
Examples:
Un-Canadian
Anti-Canadian 
Pro-Canadian 

When a prefix ends in one vowel and a root word begins with a 
different vowel, don’t hyphenate:
Example:
 
Hydroelectric, …
 when a vowel would be doubled:
Examples:
Microorganism
Anti-investigation 
Anti-intellectual
Semi-independent but semiconscious

In this case, the prefixes pre, de, pro, co, and re give solid 
words by doubling the vowel (e and o).
Examples:
 
Coordinate 
Preexist  

Exceptions: co-owner and de-emphasize, pre-empt, pre-eminent, …

To avoid tripling a consonant in compound word.
Examples:
Shell-like, Bell-like 
To  attach a prefix to a hyphenated compound word.
Example:
Non-well-known  
 To a word that might be misread or difficult to read 
without the hyphen.
Examples:
Un-uniform
Post-stall
Sub-subcommittee
When it means not, in is not hyphenated as a prefix. 
Otherwise, it does. 
Example:
 
In-service


Using the suffixes:
 
Separate the parts of a compound word using the suffixes:

Use a hyphen to avoid tripling a consonant.
Use a hyphen when the suffix like is attached to a 
proper noun.
Examples:
Shell-like (but childlike) 
Sit-in,  
Break-in
-elect

 
Compound modifiers:
 
Compound Modifier uses a hyphen to connect two or 
more words that precedes the word or phrases 
it modifies.

Hyphenate:

When a unit modifier is a combination of color
Example:
Yellow-while shirt 
When a unit modifier contains a past or present participle 
Examples:
Steam-cooked fish
Pre-reading
When a unit modifier contains numbers
Example:
Fourteen-years-old boy.
5-speed
When we want to show contributions
Example:
Fermi-Dirac Theory.

Don’t hyphenate: 

When the first element is an adverb ending in -ly
Example:
Satisfactorily long trip.
When the unit modifier has a letter or number designation 
as its second element
Example:
Number 7.
When the first element of the unit modifier is a 
comparative or superlative
Example:
Older best results.
When the unit modifier is a foreign phrase 
Example:
Ab initio calculation
When the unit modifier is a proper name 
Example:
North American Countries.
When the unit modifier is written between quotation 
marks 
Example:
“Last cry” device.
When the unit modifier is a scientific name 
Example:
Carbon dioxide

 

How to break words?
Words may be hyphenated at the ends of lines between syllables. 
They are proper places to break words. Avoid, if possible 
end-of-line hyphens, mainly when they are consecutive.

Some guidelines:
Divide words only between syllables. 
Don’t leave one letter at the end or beginning of a line.
Leave two-letter syllables at the end of a line.
(But two-letter endings may not be carried to the next line)
Don’t divide the last word of a paragraph, page.
Divide hyphenated compound words only at the hyphen, and a solid 
compounds at the natural breaks (before suffixes and after prefixes).