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2.02 Compound nouns and nouns in compounds

(a) Hyphenate two nouns representing different but equally important functions, i.e. where the hyphen denotes the relationship "both A and B":

  • city-state
  • comedy-ballet
  • dinner-dance
  • soldier-statesman
  • tractor-trailer
  • writer-editor

(b) Hyphenate nouns normally written as two words, when they have a modifier and when ambiguity would otherwise result:

  • colour filter but red colour-filter
  • letter writers but public letter-writers

Similarly, compound nouns normally written as a single word must be separated into their component parts and then joined to their modifier by a hyphen when the modifier applies only to the first component:

  • ironworker but structural-iron worker
  • housekeeper but lodging-house keeper

(c) Hyphenate compound units of measurement made by combining single units that stand in a mathematical relationship to each other:

  • car-miles
  • kilowatt-hours
  • light-year
  • person-day

(d) Hyphenate compounds that include a finite verb:

  • a has-been
  • a stay-at-home
  • a sing-along
  • a stick-in-the-mud
  • a Johnny-come-lately
  • a ne’er-do-well

(e) Hyphenate nouns of family relationship formed with great and in-law:

  • mother-in-law
  • great-grandfather


  • foster father
  • half sister
  • stepson
  • godmother