Is the word “borderline lunacy” a ‘stand-alone’ phrase or just an accidental combination of ‘borderline’ and ‘lunacy’?

I saw the word borderline lunacy in the scathing comment of a Republican strategist on Mitt Romney’s statement en route to London, Israel and Poland in Washington Post’s (7/31) article titled “Does Mitt Romney’s bad tip matter.”

“I find this entire trip borderline lunacy,” said one senior Republican strategist. “Why on earth is he seeking to improve his foreign policy cred when there will not be a single vote cast on that subject?”

I assume borderline lunacy simply means “crazy” or “almost insane,” and I was able to find many examples of usage of this word in Google, e.g.:

I understand that many may interpret this as borderline lunacy to suggest the fall of such an important and successful tech company. —connectedmonster.com

Nicolas Cage is on manic form as a degenerate New Orleans cop whose back injury leads him into a spiral of drug dependency and borderline lunacy. —skymovies.sky.com

However, this word is not registered in any of Oxford, Cambridge and Merriam-Webster Dictionary, nor is there entry in Ngram.

Is the term borderline lunacy a psychiatrist’s terminology? Or is it acknowledged as a popular “stand-alone” phrase, or just an accidental combination of borderline and lunacy, like a “borderline dirty joke”?

I’m tempted to use this word to some of right-wing Japanese politicians once.

Solution 1:

I agree that the strategist may have deliberately softened his claim by using the word borderline. Such a qualifier – meaning almost – avoids the implication that Romney is a true lunatic.

However, the speaker may also have been making a rather clever pun. In addition to its function as a softener, "borderline lunacy" is especially fitting, given that the topic at hand was a trip across international borders.

Either the strategist was very deliberate in choosing his words, coming up with a pun that borders on brilliant, on else he lucked into it through sheer coincidence. If asked for my opinion, I'd vote for the former.

Solution 2:

I assume ‘borderline lunacy’ simply means ‘crazy’ or ’almost insane,’...

You are absolutely correct.

...is it acknowledged as a popular 'stand-alone' phrase, or just an accidental combination of ‘borderline’ and ‘lunacy’?

It isn't a well-known idiom, but I wouldn't call it an accidental combination. I believe that the author wanted to soften the blow of describing Romney's excursion as lunacy, because that's a fairly serious accusation.

Solution 3:

In this example, the combination of the two words is coincidental. Further, the inclusion of the word "borderline" has no practical meaning.

When forming sentences to express judgment in a strong manner, a common device is the use of metaphor.

This essay is garbage.

The speaker of this sentence is not suggesting that the subject of his/her critique is literally garbage, but rather s/he is equating the quality of the essay with something repulsive and of no value.

Qualifiers may be used in addition to the metaphors.

This essay is borderline garbage.

This essay is absolute garbage.

Gramatically speaking, the meaning of these sentences is different due to the inclusion of the qualifiers. However, given no context in which the meaning of each qualifier is emphasized, the qualifiers do not change the effect of the sentences on the listener, nor do they suggest a difference of intent on the part of the speaker.

In all the above three examples, the speaker's intends to say that s/he finds the essay to be very bad. In this sentence

This essay is borderline garbage.

the meaning will not be interpreted by a native English speaker as "I find this essay to be quite close to very bad." Likewise,

This essay is absolute garbage.

will not be interpreted as "Although there are some essays which may be classified as bad in part or whole, I find the entirety of this particular essay to be bad."

Instead, the qualifiers act merely as further emphasis of the strength of the speaker's belief.

To extend the above points to the OP's example, the speaker is not suggesting that the subject of his critique is literally close to insanity. Rather he is equating actions which he does not find appropriate--the group of actions forming "this entire trip" of the subject--with those performed by someone who has not adequately considered other more effective options.

"I find this entire trip borderline lunacy,"

does not convey the meaning "While I wish to equate this trip to an action that may be performed by someone clinically insane, I will refrain from saying that about the trip in its entirety."

The use of "borderline" here merely acts to emphasize the speaker's opinion on the appropriateness of the trip.