Hansberry names the play after a line in the poem "Harlem" (sometimes called "Dream Deferred"), by the great Harlem Rennaisance poet Langston Hughes. In the poem, Hughes asks: "What happens to a dream deferred?/ Does it dry up/ like a raisin in the sun?"
While we don't see a single raisin in the play, we do see a lot of deferred dreams – and at the end, one dream fulfilled. (The poem is the play's epigraph, so you'll hear more about this in "What's Up with the Epigraph?" Also, be sure to check out Shmoop's learning guide to "Harlem.")