Negative capability is the poet's ability to remain open to uncertainty, mystery, and complexity without forcing a neat explanation. John Keats used the phrase to praise writing that can dwell in doubt, ambiguity, and contradiction instead of rushing to settle every question with logic or fact.
In poetry criticism, the term often describes a poem, or a poet's mind, that accepts what cannot be fully known and lets that openness shape the meaning.
Example
The fog kept its own name
and the speaker did not demand an answer;
he listened to the harbor bells
till the question itself became the poem.