Compound Adjectives - A Long List

  edgood  —  Grammar Tips
Here, for your reference, is a long list of the most frequently encountered types of compound adjectives and the rules on hyphenation. When in doubt, always check the dictionary.
Compound Adjective Formed With Rule on Hyphenation Example
all Always hyphenate. all-inclusive study
century Always hyphenate. twentieth-century   technology
cross Some hyphenated, some open, some closed. Check the dictionary. cross-referenced section
    cross-country skis
But: crosscut saw
fold Closed unless formed with numbers of 100 or more. tenfold increase
    100-fold increase
full Hyphenated before noun, open after noun. full-scale drawings
    The drawings are full scale.
half Most hyphenated, some closed. Check the dictionary. half-inch measurement
    half-baked plan
    halfway house
    halfhearted attempt
high, low, upper, lower, middle, mid Most hyphenated before noun, open after noun. high-volume trading
  highbrow organization   (check the dictionary!)
middle-class voters
midlife crisis
mid-Atlantic region
Mideast peace process
like Closed unless root word ends in or ll or has three syllables or more. catlike jumping ability
childlike demeanor
cathedral-like façade
number + odd Always hyphenate compounds formed with numbers (words or numerals) plus the word odd. twenty-odd pages
    360-odd days
    four-hundred-odd socks   . . .
    but, four hundred odd socks
number Always open when used to express a ratio (with the word percent). ten percent increase
100 percent change
Number + Unit of Measure Always hyphenate three-mile limit
two-week vacation
150-yard skid mark
Number + Unit of Measure + Adjective Always hyphenate two-year-old daughter
sixty-five-year-old man
two-and-a-half-year-old   child
twenty-five-foot-high wall
But: six year-old girls
Number + Number + Unit of Measure + Adjective Hyphenate the number and then the adjective twenty-four six-inch-long measurements
Number + Unit of Measure + Adjective (coming after noun) Hyphenate the number a man sixty-five years old (note plural years)
No hyphen a wall three meters high
  Hyphenate the number twenty-four boys five years old
fractional numbers Hyphenate spelled-out fractions used as adjectives. two-thirds majority
In mixed fractions, the whole number is not joined to the fraction by another hyphen. twenty-one and one-quarter miles
four and one-eighth inches
numbers Hyphenate only the numbers from twenty-one through ninety-nine. All others are open. twenty-four bottles of beer on the wall
    two hundred rock stars
over, under Closed unless the word the appears in the compound. overexposed film
  underrated basketball team
    over-the-counter stock   market
    under-the-table deal
self Most hyphenated. Closed if prefix un- is added or suffix added to self. self-confident applicant
self-conscious speaker
    unselfconscious speaker
    selfish act
    selfless character trait
wide Always closed unless cumbersome. Cumbersome compounds are hyphenated when they appear before the noun modified and open after the noun modified. statewide referendum
worldwide legal services
    university-wide crusade (comes before the noun modified)
    The crusade was university wide (after noun modified)

Previous: Compound Adjectives and -ly Adverbs

Next: Combining Various Parts of Speech