Half rhyme or slant rhyme, sometimes called sprung, near rhyme, oblique rhyme, off rhyme or imperfect rhyme, is consonance on the final consonants of the words involved (e.g. ill with shell). Many half/slant rhymes are also eye rhyme

Eye rhyme

Eye rhyme, also called visual rhyme and sight rhyme, is a similarity in spelling between words that are pronounced differently and hence, not an auditory rhyme...

s.

Half/slant rhyme is widely used in Irish, Scottish, Welsh, and Icelandic verse

Poetry

Poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning...

. Half/slant rhyme has been found in English-language poetry as early as Henry Vaughan

Henry Vaughan

Henry Vaughan was a Welsh physician and metaphysical poet.Vaughan and his twin brother the hermetic philosopher and alchemist Thomas Vaughan, were the sons of Thomas Vaughan and his wife Denise of 'Trenewydd', Newton, in Brecknockshire, Wales...

, but it was not until the works of W. B. Yeats and Gerard Manley Hopkins

Gerard Manley Hopkins

Gerard Manley Hopkins, S.J. was an English poet, Roman Catholic convert, and Jesuit priest, whose posthumous 20th-century fame established him among the leading Victorian poets...

 that it found wide use among English-language poets. In the 20th century half/slant rhyme has been used widely by English poets. Often, as in most of Yeats' poems, it is mixed with other devices such as regular rhymes, assonance

Assonance

Assonance is the repetition of vowel sounds to create internal rhyming within phrases or sentences, and together with alliteration and consonance serves as one of the building blocks of verse. For example, in the phrase "Do you like blue?", the is repeated within the sentence and is...

, and para-rhymes. In the following example the 'rhymes' are on/moon and bodies/ladies:

When have I last looked on

The round green eyes and the long wavering bodies

Of the dark leopards of the moon?

All the wild witches, those most noble ladies,

Moses ibn Ezra

Moses ibn Ezra

Rabbi Moses ben Jacob ibn Ezra, known as ha-Sallah was a Jewish, Spanish philosopher, linguist, and poet. He was born at Granada about 1055 – 1060, and died after 1138. Ezra is Jewish by religion but is also considered a great influence in the Arabic world in regards to his works...

, 12th century Hebrew poet and poetry theoretician, terms the practice of poets to use half-rhyme "donkey-rhyming".

American poet Emily Dickinson

Emily Dickinson

Emily Elizabeth Dickinson was an American poet. Born in Amherst, Massachusetts, to a successful family with strong community ties, she lived a mostly introverted and reclusive life...

also used half/slant rhyme frequently in her works. In her poem "Hope is the thing with feathers" the half/slant rhyme appears in the second and fourth lines. In the following example the 'rhyme' is soul/all.

Hope is the thing with feathers

That perches in the soul,

And sings the tune without the words,

And never stops at all.

The term 'slant rhyme' has been called into question due to its misleading meaning. A 'slant rhyme' suggests the words rhyme (which they do not) in a slanted fashion as opposed to nearly rhyming or half rhyming.