songwriter

n. composer, person who writes music and words for songs

A songwriter is someone who writes the lyrics to songs, the musical composition or melody to songs, or both. That is to say, a songwriter is a lyricist, a composer, or both. The word 'songwriter' is however more commonly used to describe one who writes popular songs than to describe a writer of art songs.
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Noun
1. a composer of words or music for popular songs
(synonym) songster, ballad maker
(hypernym) composer
(hyponym) Berlin, Irving Berlin, Israel Baline