Arrangements in classical music
The American Federation of Musicians defines arranging as "the art of preparing and adapting an already written composition for presentation in other than its original form. An arrangement may include reharmonization, paraphrasing, and/or development of a composition, so that it fully represents the melodic, harmonic, and rhythmic structure" (Corozine 2002, p. 3). Orchestration differs in that it is only adapting music for an orchestra or musical ensemble while arranging "involves adding compositional techniques, such as new thematic material for introductions, transitions, or modulations, and endings...Arranging is the art of giving an existing melody musical variety" (ibid).
http://en.wikipedia.org/wiki/Arrangement
musical arrangement
Noun 1. musical arrangement - a piece of music that has been adapted for performance by a particular set of voices or instruments
arrangement
musical composition, opus, piece of music, composition, piece - a musical work that has been created; "the composition is written in four movements"
orchestration - an arrangement of a piece of music for performance by an orchestra or band
instrumentation - the instruments called for in a musical score or arrangement for a band or orchestra
http://www.thefreedictionary.com/musical+arrangement
Arrangement (music)
From Wikipedia, the free encyclopedia
An arrangement of a musical composition is a reworking of a piece of music so that it can be played by a different instrument or combination of instruments from the original. For example, a song written for one voice with piano accompaniment might be arranged so that it can be sung in parts by a choir, or a piece for violin might be arranged so that it can be played on a clarinet instead. The person who does the arrangement may be the composer himself, or it may be someone else.
In music history, composers often published their compositions, saying that the music could be played or sung by various instruments. For example, when English composers published madrigals in the late 16th century they often stated that they could be sung by singers or played on viols (“apt for voices as for viols”). In the Classical music period a composer might publish a sonata, stating that it could be played on the violin or flute or recorder. This helped to sell more copies, because violinists, flautists and recorder players might all want to buy the music. In a sense this is not really an arrangement, because no changes have been made to the music.
http://simple.wikipedia.org/wiki/Arrangement_(music)
http://www.soundonsound.com/sos/1997_articles/oct97/arranging1.html
http://www.saffordbaker.com/2008/10/the-law-of-music-arrangements/