noun
coda
KOH-duh/ˈkəʊdə/
A final passage that brings a piece of music or writing to a close.
The pianist plays the coda that brings the piece to a close.

Etymology
A coda is a 'tail' attached to the main body of a work. The musical sense—a passage added to bring a composition to a close—connects that image to a concluding section.
In context
it's not the last sonnet they're actually two more after this one but they're more of a coda to the dark lady sequence they aren't written directly to her
More examples
- The pianist slows down slightly during the coda.
- A brief coda brings the novel back to its opening scene.
- Both songs have codas that repeat the main melody.
Forms
coda · codas