2.03 Nouns with adjectives and participles

(a) Hyphenate noun-plus-adjective compounds (in that order), whether used attributively or predicatively:

• duty-free goods
  • The goods were duty-free.
• tax-exempt bonds
  • The bonds are tax-exempt.

(b) Hyphenate noun-plus-participle compounds regardless of the position:

• snow-capped mountains
  • The mountains are snow-capped.
• a time-consuming activity
  • This activity is time-consuming.

Hyphenate noun-plus-participle compounds, Exceptions

There are a number of them, including handmade and handwritten.

(c) Do not hyphenate noun-plus-gerund compounds (present participle used as a noun); they may be written as one or as separate words:

• decision making
• power sharing
• problem solving
• deficit spending

• housekeeping
• shipbuilding
• sightseeing
• cabinetmaking

Do not hyphenate noun-plus-gerund compounds, Exceptions

• foot-dragging
• gut-wrenching

See 2.04 Compound adjectives; adjectives and participles in compounds(e) for such compounds used adjectivally.

2.05 Verbs

(a) Compound verbs may be either hyphenated or written solid. The only safe rule is to check your dictionary:

• freeze-dry
• mass-produce
• age-harden
• spoon-feed
• bad-mouth
• extra-bill

but

• waterproof
• downgrade
• sidetrack
• proofread

(b) If the infinitive form of the verb (e.g. to air-condition) is hyphenated, retain the hyphen in all other forms, except as illustrated in (c):

• The theatre was air-conditioned.
• You need an air-conditioning expert.

(c) Hyphenate gerunds formed from hyphenated compound verbs only if they are followed by a noun object:

• Dry cleaning is the simplest way to clean a sweater.
  but
  Dry-cleaning the sweater should remove the stain.
• Air conditioning is sometimes needed in summer.
  but
  Consider the cost in deciding whether air-conditioning the building is feasible.

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