English Compound - Compound Modifiers - Hyphenated Compound Modifiers

Hyphenated Compound Modifiers

Major style guides advise consulting a dictionary to determine whether a compound modifier should be hyphenated; the dictionary's hyphenation should be followed even when the compound modifier precedes a noun. Hyphens are unnecessary in other unambiguous, regularly used compound modifiers.

Generally, a compound modifier is hyphenated if the hyphen helps the reader differentiate a compound modifier from two adjacent modifiers that modify the noun independently. Compare the following examples:

• "small appliance industry": a small industry producing appliances
• "small-appliance industry": an industry producing small appliances

The hyphen is unneeded when capitalization or italicization makes grouping clear:

• "old English scholar": an old person who is English and a scholar, or an old scholar who studies English
• "Old English scholar": a scholar of Old English.
• "De facto proceedings" (not "de-facto")

If, however, there is no risk of ambiguities, it may be written without a hyphen: Sunday morning walk.

Hyphenated compound modifiers may have been formed originally by an adjective preceding a noun, when this phrase in turn precedes another noun:

• "Round table" → "round-table discussion"
• "Blue sky" → "blue-sky law"
• "Red light" → "red-light district"
• "Four wheels" → "four-wheel drive" (historically, the singular or root is used, not the plural)

Others may have originated with a verb preceding an adjective or adverb:

• "Feel good" → "feel-good factor"
• "Buy now, pay later" → "buy-now pay-later purchase"

Yet others are created with an original verb preceding a preposition.

• "Stick on" → "stick-on label"
• "Walk on" → "walk-on part"
• "Stand by" → "stand-by fare"
• "Roll on, roll off" → "roll-on roll-off ferry"

The following compound modifiers are always hyphenated when they are not written as one word:

• An adjective preceding a noun to which -d or -ed has been added as a past-participle construction, used before a noun:
  • "loud-mouthed hooligan"
  • "middle-aged lady"
  • "rose-tinted glasses"
• A noun, adjective, or adverb preceding a present participle:
  • "an awe-inspiring personality"
  • "a long-lasting affair"
  • "a far-reaching decision"
• Numbers, whether or not spelled:
  • "seven-year itch"
  • "five-sided polygon"
  • "20th-century poem"
  • "30-piece band"
  • "tenth-storey window"
  • "a 20-year-old man" (as a compound modifier) and "the 20-year-old" (as a compound noun) – but "a man, who is 20 years old"
• A numeral with the affix -fold has a hyphen (15-fold), but when spelled out takes a solid construction (fifteenfold).
• Numbers, spelled out or not, with added -odd: sixteen-odd, 70-odd.
• Compound modifiers with high- or low-: "high-level discussion", "low-price markup".
• Colours in compounds:
  • "a dark-blue sweater"
  • "a reddish-orange dress".
• Fractions as modifiers are hyphenated: "five-eighths inches", but if numerator or denominator are already hyphenated, the fraction itself does not take a hyphen: "a thirty-three thousandth part". (Fractions used as nouns have no hyphens: "I ate only one third of the pie.")
• Comparatives and superlatives in compound adjectives also take hyphens:
  • "the highest-placed competitor"
  • "a shorter-term loan"
• However, a construction with most is not hyphenated:
  • "the most respected member".
• Compounds including two geographical modifiers:
  • "Afro-Cuban"
  • "African-American" (sometimes)
  • "Anglo-Indian"
• But not
  • "Central American".

The following compound modifiers are not normally hyphenated:

• Compound modifiers that are not hyphenated in the relevant dictionary or that are unambiguous without a hyphen.
• Where there is no risk of ambiguity:
  • "a Sunday morning walk"
• Left-hand components of a compound modifier that end in -ly and that modify right-hand components that are past participles (ending in -ed):
  • "a hotly disputed subject"
  • "a greatly improved scheme"
  • "a distantly related celebrity"
• Compound modifiers that include comparatives and superlatives with more, most, less or least:
  • "a more recent development"
  • "the most respected member"
  • "a less opportune moment"
  • "the least expected event"
• Ordinarily hyphenated compounds with intensive adverbs in front of adjectives:
  • "very much admired classicist"
  • "really well accepted proposal"