Definition: Assonance is the repetition of vowel sounds in a phrase or line. It's harder to use and spot in fiction than in poetry, but it is a tool at the disposal of the fiction writer, especially in either more poetic or more comic passages. (For more information about the use of sounds in fiction, see alliteration.)
Examples:
In the sentence, "Wayne cradled his burlap sack of tools in his lap as we drove," (from Denis Johnson's "Jesus' Son"), the repetition of the æ sound in the words "burlap," "sack," and "lap," is an example of assonance.See more examples of assonance.