composer

n. person who composes musical compositions; author, writer, poet

A composer is a person who writes music. The term refers particularly to someone who writes music in some type of musical notation, thus allowing others to perform the music. This distinguishes the composer from a musician who improvises or plays a musical instrument.The level of distinction between composers and other musicians also varies, which affects issues such as copyright and the deference given to individual interpretations of a particular piece of music. For example, in the development of classical music in Europe, the function of composing music initially had no greater importance than the function of performing music. The preservation of individual compositions received little attention, and musicians generally had no qualms about modifying compositions for performance. Over time, however, the written notation of the composer has come to be treated as strict instructions, from which performers should not deviate without good reason. Performers do, however, play the music and interpret it in a way that is all their own.
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v. compose, make up; form; write; put together; typeset; come to terms; take a test

n. composer

(n.)
One who, or that which, quiets or calms; one who adjusts a difference.
  

(n.)
One who composes; an author. Specifically, an author of a piece of music.