Definition - Repeating the same sound — usually a consonant — either at the beginning of consecutive words or in words that are in close succession.
Note: Some feel that the term should only apply to consonants and that when it involves vowels it should be called assonance. However, according to the Concise Oxford Dictionary, alliteration can involve either consonants or vowels.

Example -
She sells shiny shells at the ship shop.

Etymology -
The word derives from the Modern Latin alliterationem (from ad, to + littera, letter).

Oxford English Dictionary -
The word's first citation is from 1656:
"Alliteration, a figure in Rhetorick, repeating and playing on the same letter."
(Blount, Glossographia )

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