In "public-private partnerships", should there be a hyphen or an en dash? And can you explain why?

  • Why would it be different from any other hyphenated compound? Consult whatever style guide you have been told to use: some will require hyphens for all compounds while others get a bit more complicated (Chicago wants an en-dash in "pre–World War II"), but we have no idea which you are using. See also this and this.
    – Stuart F
    Commented Jun 10 at 9:11
  • 1
    The implication is that there is no head as there is with a typical compound noun (ice-axe; mother-in-law): the word is exocentric. The two components are of exactly equal weight. The hyphenation is in this case used to show a more general relationship between A and B, not the typical 'an A type of B' relationship. Hyphens feel not quite the right choice here. But they are still correct. (Sometimes, odd symbols such as ∼ are preferred.) Commented Jun 10 at 15:56
  • Thank you for your analysis. My company doesn't have a style guide, but we often refer to CMOS. Surprisingly, the guide recommends using a hyphen. I think Edwin is correct in saying that a hyphen doesn't feel right in this sentence. Thank you again - I greatly appreciate your thoughtful answers.
    – Marie
    Commented Jun 10 at 19:55

2 Answers 2

  • public private partnership

    1. There is a partnership.
    2. This partnership is private.
    3. The private partnership is public.
    4. open punctuation ⇒ adjectives modify the noun separately
  • public‑private partnership

    1. There is a partnership.
    2. This partnership is public‑private.
    3. closed punctuation ⇒ noun is modified by one adjective
    4. MW: A Comprehensive Guide to Forming Compounds, § The Unit Modifier
  • Prefer a hyphen to “mix”/“blend” the qualities of adjectives.

    • Meanwhile certain terms become fixed by means of tradition. For example living‑room was standard, now it is living room, even though the room isn’t alive. It is possible that the open variant of PPP is/becomes predominant.
  • As to whether it is a hyphen (U+2010) or en‑dash (U+2013): This is mainly a stylistic question.

    An en‑dash is typically twice as long as a hyphen. It pushes the words further apart, sort of emphasizing that they don’t form a bond.

    For example Faddeev–Popov ghost employs an en‑dash: There are two people, Ludvig Faddeev and Victor Popov. A regular hyphen could be considered inappropriate since it is not one person whose surname is the combination of two family names.

  • I thoroughly enjoyed reading these answers. Thank you once again for sharing your expertise in English grammar!
    – Marie
    Commented Jun 12 at 23:07

Wikipedia Style guide has this to say-

  1. It is often preferable to substitute an unspaced endash for a hyphen in compound modifiers (see under "Hyphens" above) in which the parts of the compound are independent and equal elements. The dash may stand for and, or, versus, to, between...and, and so on. Examples: diode–transistor logic, Michelson–Morley experiment, Seifert–van Kampen theorem, male–female ratio, Lincoln–Douglas debate, French–German border. An en dash is not used for a hyphenated personal name (Lennard-Jones potential, named after John Lennard-Jones), nor for a hyphenated place name (Guinea-Bissau), nor with an element that lacks lexical independence (like the prefix "Sino-" in Sino-Japanese trade).


  • 1
    It's amazing what gets covered nowadays. As is this: '... originally known as the Waldorf-Astoria with a single hyphen, as recalled by a popular expression and song, "Meet Me at the Hyphen". The sign was changed to a double hyphen, looking similar to an equals sign, by Conrad Hilton (Waldorf=Astoria) when he purchased the hotel in 1949. The double hyphen visually represents "Peacock Alley", the hallway between the two hotels that once stood where the Empire State building now stands today. The use of the double hyphen was discontinued by its parent company Hilton in 2009 ....' [Wikipedia] Commented Jun 11 at 15:54

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