unattainable

adj. inalcanzable, inasequible, irrealizable

inexequible | inasequible | inalcanzable | irrealizable | difícil | ilusorio

Ex: Some recent national libraries have been founded as symbols of nationhood, with either no clear mission or a clearly unattainable one.

(adj.) = inalcanzable
Ex: Some recent national libraries have been founded as symbols of nationhood, with either no clear mission or a clearly unattainable one.