Catharsis is the emotional release a poem or other work can bring about in a reader or audience, especially through sorrow, pity, or fear followed by a sense of relief. The idea comes from Aristotle's discussion of tragedy, where strong feeling is stirred and then brought to a kind of clearing or calming.
In literary criticism, the word is often used more broadly than Aristotle's original idea, but it still points to the way art can help people feel and work through intense emotions.
Example
After the child in the poem is found safe at last,
the speaker's fear gives way to tears,
and the ending feels like a long held breath finally released.