Phrasal adjectives that consist of more than two words are often flawed in construction, perhaps because writers are hesitant to complicate a phrase with more than one hyphen. But hyphens are cheap and handy linking devices, and as these sentences show, their proper use enhances clarity.
1. “The high cost of the multi-million dollar catamarans caused many boats to drop out of the competition.”
What, exactly, is a dollar catamaran, and what does it mean to describe it as multi-million? That’s the format of the question anyone who describes the cost of something should ask before considering such a sentence complete and correct.
For one thing, the prefix multi-, like most prefixes, is almost invariably attached to another word without a hyphen (exception: if the other word begins with an i), but the resulting compound, multimillion, should be attached to dollar to modify what type of catamaran is under discussion: “The high cost of the multimillion-dollar catamarans caused many boats to drop out of the competition.”
2. “He met all the deadlines for the challenging four-week long assignment.”
The error here is the same as the second one in the previous example — the lack of a hyphen creates the impression that the last word in a phrasal adjective is itself modified by the preceding word or words. This sentence refers to a long assignment that is four weeks in nature. But long belongs with “four-week,” so it should be hyphenated to week to complete the phrase modifying assignment: “He met all the deadlines for the challenging four-week-long assignment.”
3. “The adviser some call the world’s second-most powerful man prefers to work behind the scenes.”
Second-most is a nonsensical modification of “powerful man.” Powerful is part of the ranking, so it should be part of the phrasal adjective: “The adviser some call the world’s second-most-powerful man prefers to work behind the scenes.”
4. “Listen to any song from our vast collection of twentieth and twenty-first century music.”
This invitation refers to music of the twentieth and twenty-first centuries, not century music of the twentieth and twenty-first. Twentieth is an elided form of twentieth-century, so it should be followed by a suspensive hyphen, and century should be attached to twenty-first with another hyphen: “Listen to any song from our vast collection of twentieth- and twenty-first-century music.”
5. “Business must be good for small-businessman John Smith.”
Because businessman is a closed compound, this sentence requires a different solution — but not “Business must be good for small-business-man John Smith.” Here, too, an appositive — one or more words that rename something — is mistaken for a phrasal adjective. For the sentence to work, the appositive must be reworded so that small and business can be hyphenated to modify just what John Smith is — an owner of a small business: “Business must be good for small-business owner John Smith.”