in prosody, the repetition of consonant sounds at the beginning of words or stressed syllables. Sometimes the repetition of initial vowel sounds (head rhyme) is also referred to as alliteration. As a poetic device, it is often discussed with assonance and consonance. In languages (such as Chinese) that emphasize tonality, the use of alliteration is rare or absent.

Alliteration is found in many common phrases, such as “pretty as a picture” and “dead as a doornail,” and is a common poetic device in almost all languages. In its simplest form, it reinforces one or two consonantal sounds, as in William Shakespeare's line:

A more complex pattern of alliteration is created when consonants both at the beginning of words and at the beginning of stressed syllables within words are repeated, as in Percy Bysshe Shelley's line:

Though alliteration is now a subsidiary embellishment in both prose and poetry, it was a formal structural principle in ancient Germanic verse. See alliterative verse. Compare assonance; consonance.