13. Couplet :]

Definition: Two lines in-a-row of poetry that rhyme.

Example:
"From the benches, black with people, there went up a muffled roar,
Like the beating of the storm waves on a stern and distant shore;"
...

Significance: Couplets make a poem more humorous. Shakespeare uses couplets in his plays to give for a more serious purpose and to give closure to a speech.