“Assonance: Sometimes called “vocalic rhyme,” it consists of the repetition of similar vowel sounds, usually close together, to achieve a similar effect of euphony. There is a kind of drowsy sonority in the following lines from Tennyson’s Lotos-Eaters which is assonantal:
‘The Lotos blooms below the barren peak:
The Lotos blooms by every winding creek:
All day the wind breathes low with mellower tone
Thro’ every hollow cave and alley lone,
Round and round the spicy downs the yellow Lotos-dust is blown.’
‘It seemed that out of battle I escaped
Down some profound dull tunnel, long since scooped
Through grantires which titanic wars had groined.
Yet also there encumbered sleepers groaned,
Too fast in thought or death to be bestirred.'”
Excerpted from: Cuddon, J.A. The Penguin Dictionary of Literary Terms and Literary Theory. New York: Penguin, 1992.