A work that has been edited or rewritten, in part or in its entirety, for a new use, audience, or purpose. Also, a work converted to another literary form or artistic medium to serve a different or related purpose, while retaining as much of the action, characters, language, and tone of the original as possible, for example, a novel or story adapted for performance on the stage (see these examples), a play adapted for the motion picture screen, or an engraving based on a painting. In AACR2, adaptations of texts are cataloged under the name of the adapter, or under the title if the adapter is unknown, with a name-title added entry for the original work. 

Reitz Joan M. (2004)