The phrase "original composition" refers to a piece of work, such as a song, poem, or painting, that is created by someone from their own ideas and not copied from anyone else. Full definition
This opportunity is for an individual jazz artist to advance or complete a body of original compositions. (18thstreet.org)
He wrote some fantastic songs that you would swear came out of the 80s or the 90s, but they're actually original compositions for the series. (businessinsider.com)
Her repertoire included jazz, folk and American musical standards, as well as original compositions on racial and social injustice. (wsws.org)