Assonance is the repetition of vowel sounds in words that are close to each other - this also includes diphthongs. Like alliteration, it is the sound rather than the letter used that is important.

When the speaker of John Betjeman's 'A Subaltern's Love Song' says "westering, questioning settles the sun / On your low-leaded window", the line is bound up with assonance on the e sound; like the strong alliteration and rhyme throughout, this adds to the jaunty music of the poem. More subtle is Adrienne Rich's use of the technique in the opening of 'For This', where the vowel sounds of "stir the nerves" are woven together with those of "letters from the dead" and "skeletons and petals".

Charles Tomlinson's poem, 'A Rose for Janet', opens with a sustained display of assonance.