A word meaning both “crucial” and “elusive”

Question

A relatively common annoyance I find is this: A person will make a list of requirements for something, and one of those requirements is both crucial and very difficult to obtain. Let’s call this characteristic “X”. Besides the X requirement, the other requirements are either (1) relatively easy to get and/or (2) not as important. The problem is that the list-maker will act like the “X” requirement is just another item on the list, when in fact, the “X” requirement should be written first on the list, bolded, and written in all caps. The "X" requirement is the first thing people should read -- it utterly disqualifies the most potential matches.

Here’s an example: I recall reading in a local paper the 5 requirements of owning and operating a yacht: (1)a willingness to learn new things, (2) good seamanship, (3), a love of the outdoors, (4),substantial disposable income and (5) sobriety. Clearly #4 isn't on-par with the other items. The “X” requirement is not only non-negotiable , but also very difficult for an ordinary person to overcome.


The world of dating is replete with this. Just recently a female acquaintance of mine who dates only very good-looking men making over 150k a year posted a dating ad where she lists these requirements, but the header says “Must love my cat and be drug-free”. I wanted to tell her that in a more practical dating world, people would list their “X” requirement in the header. But is there a proper word for “X”?

Answer 1

Probably dealbreaker/deal breaker (absence of a preferred condition or presence of an unpreferred condition) comes close.

From macmillandictionary.com:

dealbreaker NOUN [COUNTABLE]

a factor or problem that will prevent someone from agreeing to something, doing something, or buying a particular product

We’re of different religions and unfortunately that is a dealbreaker for me.

The high monthly fee for a limited service is probably a dealbreaker.

From urbandictionary.com:

deal breaker

A deal breaker is ‘the catch’ that a particular individual cannot overlook and ultimately outweighs any redeeming quality the individual may possess.

The deal breaker was that he was married with kids and I don't condone adultery.

From psychologytoday.com (The Top 9 Relationship Deal Breakers):

When we think about the kind of person we’d like to date, we often list the qualities we most desire in a partner—our dealmakers. But we also have our deal breakers—qualities that would disqualify someone as a dating prospect, regardless of how many other wonderful traits they have.

Answer 2

Perhaps the term ethereal best characterizes what you look to encapsulate in a word.

'Extremely delicate and light in a way that seems too perfect for this world.'

I say this because the 'X' factor you speak of, this quality that is hard or even impossible to obtain. This word definitely answers the elusive part, but not quite the crucial part. Still looking.

Oxford American College Dictionary