pre-noun adjectival
unfinished; unfulfilled; impossible to see through
Literary pre-noun adjectival (rentaishi) used with nouns like 夢 (dream) or 望み (hope) to express something that remains unattained or cannot be fully realized. Often carries a poetic or wistful tone.
I keep chasing an unfulfilled dream.
That was an impossible hope.
unfulfilled dream; impossible dream
From the negative form of the verb 見果てる (to see something through to the end). The classical negative auxiliary ぬ attaches to the continuative form 見果て, yielding a literary pre-noun adjectival meaning 'not seen through to the end'.