The Hyphen ( - hyphen )

The hyphen is used mainly to separate single words which make up a compound See the glossary definition (compound adjective: light-blue, compound noun: self-help). Not all compounds are hyphenated. For example, compound nouns may be separate words (contact lens), hyphenated words (self-help), or single terms (screwdriver). There are no rules about this; if in doubt, consult a dictionary.

1. Compound words

   • The sound of the ocean is also a low-frequencyadjective + noun compound sound.
   • One important pattern-makingnoun + participle process involves the way diffusing chemicals react with one another.
   • Contrary to popular belief, predators aren’t just species with large sharp teeth or fangs, hooked beaks, or razor-sharpnoun + adjective claws.
   • But Einstein suggested that gravity was the bending of something called space-timenoun + noun.
   • For instance, the giant, 160-km-widehyphens are also used to join numbers with their units and, as in this example, a dimension Chicxulub crater in Mexico that wiped out most of the dinosaurs and many other species 65 million years ago is only 1-2 kmwhen a number is uncertain, a range may be given separated by a hyphen deep and is hidden beneath younger layers of sediment.