Word for "something that is required but cannot be achieved"?

Question

Alternative definition: "something that is needed but cannot be done"

Impossible is the best I could find, but it doesn't imply that the subject is required; only that it can't be done.

An impossible task? Ridding the streets of crime is an impossible task, even for Batman. — TimR, Dec 11 '14 at 11:09
For single-word request, we ask that you list which words you didn't like (based on your search for a suitable word). Failure to do so is reason to close the question as off topic. Please add your findings by editing your question. Thanks. — anongoodnurse, Dec 11 '14 at 11:36
This question appears to be off-topic because it doesn't meet the standards for single-word requests. — anongoodnurse, Dec 11 '14 at 11:36
I agree that a proper answer would need a much better-phrased question, but you could try looking up unobtainium. — Tim Lymington, Dec 11 '14 at 12:52

score 1 · Answer 1 · edited Feb 18 '21 at 11:52

1

Pipe dream: an unattainable or fanciful hope or plan. [Lexico]

edited Feb 18 '21 at 11:52

Decapitated Soul

answered Feb 18 '21 at 11:37

frankie

1

You should include a dictionary source/link for your definition. – KillingTime Feb 18 '21 at 11:47

score 0 · Answer 2 · answered Dec 11 '14 at 12:51

0

It depends on the context. If you are writing about a goal, it might be unattainable.

answered Dec 11 '14 at 12:51

Gary's Student

score 0 · Answer 3 · answered Dec 11 '14 at 13:29

0

You could use Sisyphean. This relates to the myth of Sisyphus and describes a task that is impossible to complete.

answered Dec 11 '14 at 13:29

Patrick Wood

3 Answers3