To Hyphenate or Not To Hyphenate After a Noun: That is the Wrong Question
This job is long-term.
Do you need the hyphen here? Most authorities, rightly, say no. Don’t hyphenate a compound modifier when it follows a noun. Before a noun, yes (This is a long-term job), but after, no (This job is long term).
Most authorities also point out exceptions. They say, again rightly, that some compounds (blue-green, razor-sharp, risk-averse, time-sensitive, etc.) need a hyphen every time. When in doubt, they say, consult a dictionary or style guide.
Fine advice as far as it goes.
But most authorities don’t tell you what you most need to know. They don’t tell you that if you ask “Do I need a hyphen here?” after a noun, you’re almost always asking the wrong question.
They don’t tell you that a post-noun modifier almost always follows a be-verb (is or was or some other linking verb). And they don’t tell you that a be-verb almost always signals an opportunity to strengthen a sentence.
So when faced with a sentence like This job is long term or The suit is blue-green or That child is razor-sharp, what question should you ask? This one: “What do I have to say about that long-term job, that blue-green suit, that razor-sharp child?” Eliminate the is, and swap in some substance—This long-term job pays more than anyone in Joan’s family has ever made or Donovan thought that the blue-green suit made the professor look glamorous or Those razor-sharp kids speak twelve languages. Then, maybe, you’ll have yourself a sentence worth reading.